Fastest way to remove 6.2 diesel

[campfire]

OM Mercedes motor?

I do not remember what series the engine came from, but yes, it was a 3-liter 5-cylinder Mercedes. I always thought the throttle valve was a little redundant, but the idea has come back in style again as a way to smooth out the abrupt stopping upon shutdown that diesels are famous for. So maybe they were just ahead of their time?

As for the vacuum regulator, GM built theirs into the TPS, so they still only needed one control cable. That linkage mechanism crossing over the engine burned a considerable amount of real estate.

 

[campfire]

Here is a sample photo of what I'm talking about. Pivots, links, shafts, and one interesting slot joint on top of the valve cover. Push the STOP button to stop, pull it toward you to advance the throttle. Terrible? No, it's still funner than working on many modern cars. But it does look goofy to these eyes. That engine compartment would have so much more space if they had used a simple cable mechanism.

 

[cadmo]

Ya thet seems way to complex for the time.

 

[campfire]

Ya thet seems way to complex for the time.

This is the one that I kept. One cable, one wire. Dirt simple. (Although, since this is a 700R4 truck, I guess I do have 2 cables instead of one, but I avoid the vacuum regulator altogether).

There is certainly a place for complicated designs. But I think MB struck out this time.

 

[diesel4me]

At least it looks like on the Mercedes you might be able to remove the valve cover without taking off every injector line,intake,and just about every other part on top of the engine..unlike a 6.2,which requires at least a full 8 hour day to do,(at least it would take ME that long)-and chances are after you re-assemble everything (assuming you didn't break an injector line or do other damage to parts like injectors,strip threads,bust off bolts,etc..)--the dam covers will leak again soon,if not immediately..that's a lot of work for a job that might well be a "fail"..

That is one of several reasons I'm tempted to swap a gas engine back in my truck--IF I even fix it ,period..a leaky valve cover gasket is a half hour job tops on most gas V8's or straight sixes,on a 6.2 its miserable enough to make me want to scrap the truck instead of attempting to fix it..(and a square body is considered "easy" to work on compared to anything newer,but not when it has a diesel,IMO-)..

I too long for simplicity and easy to work on designs like they had back in the 60's and 70's..toadys vehicles just plain suck to work on,and for no good reason..they COULD design things better from a serviceability viewpoint,but they dont..that might make people more likely to maintain their vehicles and decrease sales of new ones..

 

[campfire]

At least it looks like on the Mercedes you might be able to remove the valve cover without taking off every injector line,intake,and just about every other part on top of the engine..unlike a 6.2,which requires at least a full 8 hour day to do,(at least it would take ME that long)-and chances are after you re-assemble everything (assuming you didn't break an injector line or do other damage to parts like injectors,strip threads,bust off bolts,etc..)--the dam covers will leak again soon,if not immediately..that's a lot of work for a job that might well be a "fail"..

That is one of several reasons I'm tempted to swap a gas engine back in my truck--IF I even fix it ,period..a leaky valve cover gasket is a half hour job tops on most gas V8's or straight sixes,on a 6.2 its miserable enough to make me want to scrap the truck instead of attempting to fix it..(and a square body is considered "easy" to work on compared to anything newer,but not when it has a diesel,IMO-)..

I too long for simplicity and easy to work on designs like they had back in the 60's and 70's..toadys vehicles just plain suck to work on,and for no good reason..they COULD design things better from a serviceability viewpoint,but they dont..that might make people more likely to maintain their vehicles and decrease sales of new ones..

Hate to burst your bubble, but that lovely linkage system sits on top of the valve cover, so it's not a half hour job here, either.
Nor are these engines immune to oil leaks.

Have you done a valve cover on a 6.2 before? It does not require removing the intake. The injector lines are the only additional headache vs. a small block. I disconnected the injector ends of the lines and gently bent them up a couple inches, and then slipped the valve cover out the lower side. Is it as fun as other engines? No, not really. But it's hardly an 8-hour affair. I think you could snap an injector line, tear the intake area apart to replace it, and it still shouldn't be an 8 hour job. At least, not for a shop. YMMV.

 

[campfire]

The part that I find annoying is that the intake side of the head does have room for injectors, they could have moved the prechamber to that side and had all of the injection system under the intake. It wouldn't have been any more buried (you already hafta take off the intake to get to the lines or the IP), and it would have totally eliminated the valve cover nightmare AND also made the exhaust easier to work on. And exhaust is the nasty side of most old engines, IMO. Assuming they moved the GPs inboard, it would eliminate the fried GP wire problem that some of these trucks have.

Looking back, it looks so obvious to me. I wonder what sort of internal process went into that decision.

 

[diesel4me]

I've never removed a valve cover on a 6.2 and don't want too,especially on mine,which has most every bolt rusted enough to not be the original sized head it had,and chances of one breaking off are good..

I don't think I'd risk trying to fudge it by just taking the injector lines off at the injectors and bending them up some either,not only are they rusty enough at the flare nut to likely twist off the tubing instead of unscrewing,they also have a "liner" inside the tubing that can flake off if bent,and clog up the injector..not saying that method could not be done with success--just not likely on mine..also the valve cover bolts hold the injector line "clamps"--I tried loosening the bolts and the whole thing wants to turn and twist the lines up..I'd ruin a lot of expensive hard to get things trying to fix a stupid oil leak...

I do have some spare lines,but would rather not have to screw with them..my back is still quite fubared from the exhaust manifold deal 3 weeks ago too..

I too do not know why they couldn't have located the injectors on the "inside" and that would not only ease valve cover removal,the stupid rubber return line hoses wouldn't be positioned right over the nice hot exhaust manifold and turn into flame throwers if one should fail or come off..
They could have made the heads better too--the way the valve covers slant down towards the ground at such an angle,only increases the chances of oil leakage,especially in the rear,and it also makes for a miserable job of removing or installing the exhaust manifold bolts..especially when the bolts are too close to the frame rail to allow use of a ratchet,or even a breaker bar..

I litteraly had to use a cutting torch to cut the manifold off my engine,no way any wrench was going to grab bolt heads that looked like rivets..and if one busted off in the heads you'd be screwed,no drill can get at those exhaust ports that face down at the frame,3" away..

Between the rotted oil pan,leaking valve cover that is coating the exhaust manifold and front pipe with oil,and the inner fenders being roached on my truck,the "best" way to repair it would be to take off the nose and pull the engine right out--IF I were able to do all that..

Then I might as well do head gaskets,IF the heads are good,and no cracks are found in the block or heads--then, after all that agony it could well spin a bearing or snap the crank a week later,with my luck....this is why I'd rather just limp along with jerry rigged fixes and or just get a running 350 or inline six to put in it..

 

[cadmo]

Diesel4me i feel your pain of rusted bolts. My drivetrain is rust fee due to the previous owner letting the trany cooler lines leak and blow oil everywhere. Its got a nice oil sludge / dirt build up that loves to go in my hair and eyes working under it.

BUT where the oil didnt get on the body i have rust everywhere with sheared bolt heads. And a nice pile of rust i could donate to the nearest beach.

 

[cadmo]

But on another note got the front clip off and i love how much more i can see with it off. A guy on pirate did a build with no lift and huge tires kept the front clip off for better visibility, kinda liking that idea now.

 

[diesel4me]

That sounds familiar..

The only un-rusted parts under my truck are part of the cab floor ,and some other areas near it where the oil leakage from the engine got blown back and "undercoated" it..

Overall the cab has some rot but its not extensive,the rockers are still original but have patches now,and roof of the truck had more rot than the rest of it when I got it,and still does--I think a tree fell on the roof before I got it,and the hack who "fixed" it just troweled a few gallons of bondo over the entire roof,which is now chipping off and is quite thick..

The frame once still had that factory asphalt coating on it when I got it,now most of it has come off and it is heavily surface rusted,but at least 90% of it is not rotted thin or in danger of failing..(of course that can change quickly too)..

But most of the fasteners are rusted enough to make removal difficult to impossible,I have to use "bolt out extractors" you pound over rusted bolt heads in order to be able to unscrew any of them,and your lucky if you have room enough to use those,being 3/4" hex,much of the time you cant get one in a tight spot (like a valve cover bolt)..the blue wrench is the one I end up using most often on my vehicles thanks to salt and a moist climate..

Another discouragement as far as me doing my own repairs is the fact my eyes now have artificial lenses in them (after cataract surgery)--not only does that affect my vision a lot at arms length--I am very fearful of getting something in them --(dirt,grease,oil,rust flakes,chemicals etc-)--I already got some oven cleaner and brake & carb cleaner in them while attempting to clean the oil pan well enough the other day, to get "anything" to stick to it like RTV,Bondo,whatever else might work,to at least slow down the leakage..it's not worth risking losing my sight over it,that's for sure..

 

[campfire]

The frame once still had that factory asphalt coating on it when I got it,now most of it has come off and it is heavily surface rusted,but at least 90% of it is not rotted thin or in danger of failing..(of course that can change quickly too)..

Interesting. I have no asphalt coating on my '83 frame, but I can still see most of it on the '84 frame. I had figured that it was something added in '84. I guess not.

 

[Stomis]

Here is a sample photo of what I'm talking about. Pivots, links, shafts, and one interesting slot joint on top of the valve cover. Push the STOP button to stop, pull it toward you to advance the throttle. Terrible? No, it's still funner than working on many modern cars. But it does look goofy to these eyes. That engine compartment would have so much more space if they had used a simple cable mechanism.

OM617 I knew it as soon as you said it LOFL. Ok hijack over.

 

[diesel4me]

Interesting. I have no asphalt coating on my '83 frame, but I can still see most of it on the '84 frame. I had figured that it was something added in '84. I guess not.

No way to know if the frame on my '82 was factory sprayed with that asphalt goop,but I assume it was...my '85 Burb has that on the frame too,and what appears to be glossy black paint underneath,but since the rest of the truck was heavily undercoated previously ,most likely not by GM,its a good bet its not the original coating..but who knows for sure ?..

 

[Joe In Montana]

Much ado 'bout little.

Pull the engine after you jack the bellhousing hard into the firewall and pull the engine with the converter attached. It's not going to destroy anything if you use a modicum of grey matter and pay attention to keeping things somewhat in line....-convertor-wise, that is.

Notice: there WILL be ATF on the floor. Be ready with a lot of poop-n-scoop kitty litter.

I've had customers drag vehicles in with just this same seized engine problem AFTER they failed to get it out and only once or twice do I remember having to do anything more than replace the front seal .... which you're gonna do anyway.

PLEASE say you are going to at least replace the front seal....right?

And anyway... a front pump is easy to replace if it's needed. I tend to at least reseal the front pump and install a new bushing and a look/see into the pump won't hurt either. At that time, I drill out the drain back hole and deburr the crossover plumbing casting sprue at least.

These above experiences were with idiots, and you're not an idiot since you are up-front in asking for advice..... idiots, otoh.... never ask for advice.

FWIW .... the convertor isn't that deep into the front pump anyway. Just don't try to put the engine back with the converter bolted to the flexplate.

THIS (^) I'VE SEEN............. and it ain't pretty.

 

[scpaul]

C4 cures alot of things, sorry but I just had to. Paul

 

[cadmo]

Ok so i got it out and all i can say is i hate the f@ukin thing. Unbolting the trany was pretty easy by its self. But with saggy springs the starter was impossible to get out, the stupud bracing in the way from the tcase and then on the sides of the engine to trans. And my trans cooler lines got bent, who designs the port on the passenger side then crosses over to the driver side all along the belhousing and oil pan. They could have done a straight shot forward.

At age 17 i made my firebird v6 auto to v8 manual with no help or instructions or internet. Its was way easier than removing the pos engine.

Oh and the mess it makes, my warehouse is filthy.

Thats my rant for the night...

 

[ChrisPerry]

Ok, engine is officially out. Time to drink beer and relax

 

[Joe In Montana]

About that starter removal on a 6.2.

I put a small bottle jack between the spring or axle and the frame and jack it up to open the gap under the starter.

WARNING - WARNING!
The following is for people who
love their 6.2L diesel engines.

All others can stop reading here.
You've been warned.
and there's lots of big words too.

​

For a while I worked exclusively on the GM 4.3, 5.7 and 6.2 diesels and found that they had a few engineering quirks that for the most part could be fixed or re-engineered if you will.

I'll concentrate of the 6.2s here.

In the spread of California and Federal and Canadian specs and designs, if you have an Oak Leaf on the driver's door pillar - then you've got a superior engine that already has more horsepower than either the CONUS or especially the CalEPA certified versions.

For reasons that escape my ideas of doing it right, the California models have a severely retarded camshaft and the injectors are smaller and pop off at lower pressures.

The injection pump has a stop inside the advance piston to keep total advance small.

The camshaft was retarded a full 10-12 degrees after TDC which made the 0 degree timing for injection actually much later. The mantissa marks on the injection pump mounting flange was supposed to be set on the mark with the injection pump adapter that went into the top of the timing gear hump.

That was to get the injection pump to at least get fuel into the combustion chamber soon enough to actually make it burn, but it was late and created a lot of heat at the exhaust valve pocket and this is usually where the stock head bolts and/or OE (I think they were McCord cheapie) head gaskets failed.

The compression ratio, albeit the ADVERTISED 12.75:1 compression ratio is actually lower than stated for another arcane reason. It's prolly to burn that CalDiesel which had the paraffin taken out of it and then a good dose of ethanol put into it - which resulted in huge lawsuits that had an expiration date a long - long - lo-ong time ago.

Historical Note: California bit the big one and paid $$$ for all the diesel pumps and injectors they ruined for that mistake.

Compression tests that I personally performed on these California engines indicated the CR was more like 11.5:1 or so.

Enter the 6.2D CONUS - or more correctly called the FEDERAL version that had a more advanced camshaft - but it was still retarded about 6 or 8 degrees after TDC.

The injectors had more realistic pop off pressure but the nozzles were still pretty small.

This engine made a little more power but was also a loser in the horsepower ratings - having instead a lot more torque about which it boasted.

The tested CR was around 13:1 or so - but still too low for any power or performance in my opinion.

Now the true Canadian engines - with the identifying Oak Leaf on the door pillar to make it more recognizable - had the camshaft set at ZERO and the injectors had seriously more pop off pressure and bigger nozzles. The compression was a full point-and-a-half higher - although rumors had it that the Oak Leaf versions at a full 22.5:1 - which would be radical at least!

So - where am I going here?

If one has an Oak Leaf 6.2D and they want to stay with diesel - these can really be made to run some serious torque and horsepower with a few updates and no added turbocharger.

First - the Roosa-Master/Stanadyne pump need to be built by someone who knows and is certified as a true Roosa-Master/Stanadyne builder - not some guy building them on a benchtop in his garden shed. Tell the certified shop that you want it to RUN HARD and max out the advance piston by machining the piston stop button and turn up the cranking fuel delivery.

Then get a really good surface on the head to cut it down about 0.080" for some real compression.

NOTICE - SIDEBAR HERE: Do NOT cut the California or (possibly too) the FEDERAL heads as they are lighter for weight of the engine package concerns like the Ford/IHC 6.9-7.2 which Ford cut about 225 lbs out of the engine to help the front end hold it up.

The cam is unfortunately not a big ticket performance item and therefor it has never and prolly is not being custom ground by but a few cam grinders. These are real roller cams and they can be pretty radical in duration to make them pop some more power.

Replace the head bolts with shouldered Grade 12 studs - course threads only, and use new Sched.80 Vascomax washers.

Liberally coat all the threads that go into the block anywhere with Permatex #303 Aviation type sealer.

Use FelPro gaskets throughout. Try to find the PURPLE Perma-Print gaskets.

The oil pump is more than capable for anything you can ask the engine to do so don't sweat it.

Put a smaller diameter convertor on the transmission - if automatic - to raise the stall speed and make sure it has 6 convertor bolts or studs. No less.

Remover the EGR system - even though I know it works - but it kills the engine after a while. Sorry 'bout that!

Do not use Champion glow plugs.You'll be sorry if you do.

Lube oil by Rotella or Delo is fine as you have a roller engine here that even cow urine could lubricate well.

If you have a manual transmission, then use a diaphragm type clutch since it will hold just fine and yet you can almost push the pedal down with your hand. It's lots easier on the drivetrain and the clutch linkage - and driver fatigue too.

This diaphragm type clutch seems wrong on many fronts - but after taking care of a fleet of tow trucks with both gas and diesel engines in GMC/Chevy 2500, 3500 and 4500 series bodies with all the tow truck cr@p on them - they lasted a lot longer than the B-W or B&B clutches.

[/soapbox]





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[campfire]

About that starter removal on a 6.2.

I put a small bottle jack between the spring or axle and the frame and jack it up to open the gap under the starter.

WARNING - WARNING!
The following is for people who
love their 6.2L diesel engines.

All others can stop reading here.
You've been warned.
and there's lots of big words too.

​

For a while I worked exclusively on the GM 4.3, 5.7 and 6.2 diesels and found that they had a few engineering quirks that for the most part could be fixed or re-engineered if you will.

I'll concentrate of the 6.2s here.

In the spread of California and Federal and Canadian specs and designs, if you have an Oak Leaf on the driver's door pillar - then you've got a superior engine that already has more horsepower than either the CONUS or especially the CalEPA certified versions.

For reasons that escape my ideas of doing it right, the California models have a severely retarded camshaft and the injectors are smaller and pop off at lower pressures.

The injection pump has a stop inside the advance piston to keep total advance small.

The camshaft was retarded a full 10-12 degrees after TDC which made the 0 degree timing for injection actually much later. The mantissa marks on the injection pump mounting flange was supposed to be set on the mark with the injection pump adapter that went into the top of the timing gear hump.

That was to get the injection pump to at least get fuel into the combustion chamber soon enough to actually make it burn, but it was late and created a lot of heat at the exhaust valve pocket and this is usually where the stock head bolts and/or OE (I think they were McCord cheapie) head gaskets failed.

The compression ratio, albeit the ADVERTISED 12.75:1 compression ratio is actually lower than stated for another arcane reason. It's prolly to burn that CalDiesel which had the paraffin taken out of it and then a good dose of ethanol put into it - which resulted in huge lawsuits that had an expiration date a long - long - lo-ong time ago.

Historical Note: California bit the big one and paid $$$ for all the diesel pumps and injectors they ruined for that mistake.

Compression tests that I personally performed on these California engines indicated the CR was more like 11.5:1 or so.

Enter the 6.2D CONUS - or more correctly called the FEDERAL version that had a more advanced camshaft - but it was still retarded about 6 or 8 degrees after TDC.

The injectors had more realistic pop off pressure but the nozzles were still pretty small.

This engine made a little more power but was also a loser in the horsepower ratings - having instead a lot more torque about which it boasted.

The tested CR was around 13:1 or so - but still too low for any power or performance in my opinion.

Now the true Canadian engines - with the identifying Oak Leaf on the door pillar to make it more recognizable - had the camshaft set at ZERO and the injectors had seriously more pop off pressure and bigger nozzles. The compression was a full point-and-a-half higher - although rumors had it that the Oak Leaf versions at a full 22.5:1 - which would be radical at least!

So - where am I going here?

If one has an Oak Leaf 6.2D and they want to stay with diesel - these can really be made to run some serious torque and horsepower with a few updates and no added turbocharger.

First - the Roosa-Master/Stanadyne pump need to be built by someone who knows and is certified as a true Roosa-Master/Stanadyne builder - not some guy building them on a benchtop in his garden shed. Tell the certified shop that you want it to RUN HARD and max out the advance piston by machining the piston stop button and turn up the cranking fuel delivery.

Then get a really good surface on the head to cut it down about 0.080" for some real compression.

NOTICE - SIDEBAR HERE: Do NOT cut the California or (possibly too) the FEDERAL heads as they are lighter for weight of the engine package concerns like the Ford/IHC 6.9-7.2 which Ford cut about 225 lbs out of the engine to help the front end hold it up.

The cam is unfortunately not a big ticket performance item and therefor it has never and prolly is not being custom ground by but a few cam grinders. These are real roller cams and they can be pretty radical in duration to make them pop some more power.

Replace the head bolts with shouldered Grade 12 studs - course threads only, and use new Sched.80 Vascomax washers.

Liberally coat all the threads that go into the block anywhere with Permatex #303 Aviation type sealer.

Use FelPro gaskets throughout. Try to find the PURPLE Perma-Print gaskets.

The oil pump is more than capable for anything you can ask the engine to do so don't sweat it.

Put a smaller diameter convertor on the transmission - if automatic - to raise the stall speed and make sure it has 6 convertor bolts or studs. No less.

Remover the EGR system - even though I know it works - but it kills the engine after a while. Sorry 'bout that!

Do not use Champion glow plugs.You'll be sorry if you do.

Lube oil by Rotella or Delo is fine as you have a roller engine here that even cow urine could lubricate well.

If you have a manual transmission, then use a diaphragm type clutch since it will hold just fine and yet you can almost push the pedal down with your hand. It's lots easier on the drivetrain and the clutch linkage - and driver fatigue too.

This diaphragm type clutch seems wrong on many fronts - but after taking care of a fleet of tow trucks with both gas and diesel engines in GMC/Chevy 2500, 3500 and 4500 series bodies with all the tow truck cr@p on them - they lasted a lot longer than the B-W or B&B clutches.

[/soapbox]





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Knowledge noted and packed away for potential future use.