Addressing 6.2L Oil leak(s)

[diesel4me]

I'm tempted to put a quart of Lucal "oil stop leak" goop in my engine,or the plain Lucas oil treatment--but I'm afraid it'll be like mud in sub-freezing temps--it has a hard enough time cranking over with just straight 15W-40 in it..especially with the two batteries that have been in it 13 years and are now failing..

Last year I was losing enough oil from the leaky pan and wherever else ,that I was adding a quart every 50 miles or so...

I began using oil drained from cars out of my friends used oil barrels at his shop,I couldn't see spending 5 bucks a quart daily,just to piss it on the ground..--most of the cars he does oil changes on used synthetics (BMW's,Mercedes,etc)..the oil was a mixture of all different viscosity,like 5W-30,10W-30,and probably more synthetic than conventional...
My oil pressure was lower running it on that stuff-in fact, in hot summer weather the gauge showed only 10-15 psi at idle when I'd normally see 25-30 psi-but it started a lot easier in the winter,being thinner,and the engine seemed a lot quieter too...as soon as I got the leaks to a minimum I changed the oil back to 15W-40 and it now cranks over like its grease in the crankcase first thing on a frigid morning again..and sounds like every moving part is too small for the holes they fit into for a good 10 minutes or so....

I'm going to have to leave the battery charger on the truck this weekend--lows near 10 degrees and 25 by day,with 6-12" of snow expected Saturday night--getting 2-4" as I type this now...looks like I'll have to go put the plow on it later.....hate snow!....

 

[B.barket]

I'm tempted to put a quart of Lucal "oil stop leak" goop in my engine,or the plain Lucas oil treatment--but I'm afraid it'll be like mud in sub-freezing temps--it has a hard enough time cranking over with just straight 15W-40 in it..especially with the two batteries that have been in it 13 years and are now failing..

I'm going to have to leave the battery charger on the truck this weekend--lows near 10 degrees and 25 by day,with 6-12" of snow expected Saturday night--getting 2-4" as I type this now...looks like I'll have to go put the plow on it later.....hate snow!....

^^ I hear ya' on hating the cold!.. As I get older my tolerance and patience for it is less and less.. I love to play in the snow on my terms.. Skiing, sledding, even just bein' outside on a snowy day can be enjoyable.. But working and living your day to day life in it certainly can be a challenge at times.. Heck, I'm dying to tear into this little valve cover project but its just to damn cold right now.. My shop isn't insulated whatsoever so warming it up really ain't an option.. Does the Lucas "oil stop leak" and products like it really work?.. I don't think I'd use any as I won't be driving the truck again until spring.. Just curious about how well they work since you mentioned it..

 

[campfire]

Bob, my Suburban popped off at 10 degrees this week after sitting for months. That's running 1 quart of standard Lucas oil treatment in the pan. The leaks slowed and the oil did thicken. On my TinyCar I have taken it too far, running 30 and 40 wt. in the summer and not swapping it out fast enough in the winter. Slow cranks and a couple second wait for oil pressure on a bitter cold morning. So you can overdo it if you're running sludge. For this first oil change, I'm running normal 10w30 in the Blazer, and it is quite happy in the cold compared to the 10w40 trucks. Don't remember if I put Lucas in there or not.

 

[campfire]

FWIW, adding Lucas to my little Saturn slowed my leak rate from one quart every 1000 miles to one quart every 2500 miles. Not eliminated, but slower than it had been. Later the 30 and 40 wt. oils got really cheap and it made more sense to let it leak at a medium rate with the super cheap stuff. YMMV.

 

[longbedder]

I have a truck that liked to mark its territory. While I'm fine with establishing a little dominance, it got annoying cleaning the driveway when I went to sell our house. A pressure washer is no match for a couple years of used Delo 400

Anywho, over the years I discovered the following:
-An injection pump leaking out the throttle shaft will send diesel fuel into the valley, which will then flow down and collect crud from the engine and bellhousing then drip - it looks, feels, and smells just like an engine oil leak. It also really means it's time to rebuild your IP
-The rear main seal for the 6.2 is an old-school hemp-rope type, and it will leak. Replace it with a Fel-Pro neoprene seal (PN: BS40529).
-When you replace your rear main seal, ditch the oil pan gasket and just use The Right Stuff to seal both the rear main seal to engine block, as well as to seal the pan itself. Put a new oil pump while you're in there because [Why Not?]
It'll also give you the opportunity to see if your block has the infamous main bearing web cracking.
-Oh, and while you've got the pan off, you may as well pull the front covers and put a new timing set, water pump, and crank seal on also...amiright?

Did all that a few years ago and not a drop since.

 

[diesel4me]

My 6.2 failed to start last Sunday,after we got about 14" of snow with deeper drifts--it cranked over and "almost" fired up,then the batteries started dying and it wouldn't crank fast enough to get it started..

I didn't bother taking the snow or the tarp I draped over it off,figured it was futile to try jump starting it with two other half junk batteries I keep around for starting my garden tractors..ended up using a tractor with a snowblower to clear the entire 110 x 30 foot "Y" shaped driveway--which took 5 hours,in the 5 degree cold with gusty wind chills..

Yesterday when I awoke at 6 am,the driveway was BARE,and it was 55 degrees all day--and it is 60 here now!..wasted all that effort and a 20 dollar V-belt for the snowblower,just to have it melt 3 days later--but if I had left it,you can bet more would have fallen..

Before I'd do all that to stop the leaks on my 6.2--replace the oil pan,the valve cover gaskets--put in an oil pump "while I'm in there",and fix all its other things about to fail,(and God forbid I'd ever need to mess with the injector pump,etc !)----I'd just put a gas engine back in it--be cheaper and I'd like the truck a lot more...then it might start with no hassles in the cold..and not leak..

This diesel has been put thru hell even before I got it,(was a salvage yard replacement of unknown mileage or vintage)--and I'd hate to spend a nickel fixing it when it may well have cracks,or other big problems brewing inside it..I'm just going to keep it full of oil,run it,and hope it holds together awhile longer..

My driveway has been ruined in a few spots due to leaking oil and ATF,gear oil, .from several vehicles.

I used a 3500 psi pressure washer once to try and wash the oil off,and the top layer of asphalt blew off with it...some spots went right down to gravel!...would have been better off to either left it alone,or poured gas on it and lit it up,and let it burn...I tried that in other spots and it worked better than I thought!..

 

[B.barket]

I have a truck that liked to mark its territory. While I'm fine with establishing a little dominance, it got annoying cleaning the driveway when I went to sell our house. A pressure washer is no match for a couple years of used Delo 400

Anywho, over the years I discovered the following:
-An injection pump leaking out the throttle shaft will send diesel fuel into the valley, which will then flow down and collect crud from the engine and bellhousing then drip - it looks, feels, and smells just like an engine oil leak. It also really means it's time to rebuild your IP
-The rear main seal for the 6.2 is an old-school hemp-rope type, and it will leak. Replace it with a Fel-Pro neoprene seal (PN: BS40529).
-When you replace your rear main seal, ditch the oil pan gasket and just use The Right Stuff to seal both the rear main seal to engine block, as well as to seal the pan itself. Put a new oil pump while you're in there because [Why Not?]
It'll also give you the opportunity to see if your block has the infamous main bearing web cracking.
-Oh, and while you've got the pan off, you may as well pull the front covers and put a new timing set, water pump, and crank seal on also...amiright?

Did all that a few years ago and not a drop since.

Thanks for this post.. That's a simple and very comprehensive list of what to do to go after the leaks plus a few other things to consider dealing with while you're at it!

 

[tRustyK5]

I have a truck that liked to mark its territory. While I'm fine with establishing a little dominance, it got annoying cleaning the driveway when I went to sell our house. A pressure washer is no match for a couple years of used Delo 400

Anywho, over the years I discovered the following:
-An injection pump leaking out the throttle shaft will send diesel fuel into the valley, which will then flow down and collect crud from the engine and bellhousing then drip - it looks, feels, and smells just like an engine oil leak. It also really means it's time to rebuild your IP
-The rear main seal for the 6.2 is an old-school hemp-rope type, and it will leak. Replace it with a Fel-Pro neoprene seal (PN: BS40529).
-When you replace your rear main seal, ditch the oil pan gasket and just use The Right Stuff to seal both the rear main seal to engine block, as well as to seal the pan itself. Put a new oil pump while you're in there because [Why Not?]
It'll also give you the opportunity to see if your block has the infamous main bearing web cracking.
-Oh, and while you've got the pan off, you may as well pull the front covers and put a new timing set, water pump, and crank seal on also...amiright?

Did all that a few years ago and not a drop since.

I did most of that with great success. I also took some time up top. I added a rebuilt IP and rebuilt injectors. This necessitated intake removal, which led to gasket matching the intake with a die grinder, and bead blasting the rest. The casting accuracy on these intakes is terrible, FYI. Then I did valve covers.

The thing is, you're opening a can of worms. Where do you stop? Ideally you pull the engine and transmission, power wash the whole thing, then dis-assemble and reseal everything, then re-install.

 

[B.barket]

Hey guys.. I'll be getting at this little project as the weather warms up in the next month or so.. As one thought leads to another I'm now considering yet another addition to the "to do" list while addressing the oil leaks.. To recap what I'm doing for sure.. I'm cleaning and or replacing my CDR and replacing both valve cover gaskets.. Then I'll evaluate the leaks from there.. If it persists, than its onto the oil pan and rear main.. Soooo.. Since I'm already tearing in to the valve covers.. I though maybe I should swap to a J Code intake while I'm at it.. Thus eliminating the CDR all together.. My 6.2 runs very well in pure stock C Code form.. Am I risking buggering it up a good running engine by swapping to a J Code?.. Should I just leave well enough alone in that area?.. If it will run stronger and healthier with a J Code, its worth it I suppose..Or if I ever want decided to turbo it I imagine the J Code is better as well.. It seems to be a very simple upgrade.. Unbolt one, bolt on the other and you're done.. Correct?.. Beyond that, maybe have an exhaust shop install a cross over pipe between the true dual exhaust.. Is there anything else to so for this swap besides that?.. If I simply disconnect the CDR hoses and put a frost plug un the hole in the intake am I accomplishing the same thing?.. Or if I just ordered the J code intake gaskets that block off the exhaust ports is that the same thing?.. I know this C code J code intake thing is a bit of a can of worms to open.. But all opinions are welcome and appreciated!

 

[diesel4me]

I have a J code intake on a blown up '87 6.2 (busted crank) I got for spare parts...have been tempted to swap it on my C code 6.2,but haven't yet...

I'm not sure,but I think they still need a CDR valve with the J-code intake.I'm pretty sure that J code intake has one,though its a bit different than the C-code one on my pickup..

The CDR valve does much the same thing as a PCV valve on a gas motor,and just blocking off the ports may not work,it will likely build pressure up in the crankcase and increase the risk of excess blow-by,leaks at gaskets & seals, and even create a "runaway" condition...that is when a diesel starts running off the crankcase oil & fumes and cant be shut off ,unless you "smother" the intake with something..

I've had fears of that happening to one of my diesels--go on youtube and look under "runaway diesels" and you'll see what I mean--a diesel going 7000 rpms with no means to stop it is a very frightening experience I'm sure--one I hope to never have first hand!....

 

[longbedder]

Yeah, you'll still want a CDR regardless of intake style. Without one, the oil in your crankcase will find the path of least resistance out of that engine.

I don't know how much difference the famous C- to J-code intake really makes. If it's cheap or free then sure...but it's still a naturally aspirated ~120HP diesel engine.

 

[diesel4me]

Most C-code 6.2's were 140 HP and 230 ft/lbs torque..
Mine feels more like 100 HP now,and maybe 180 ft/lbs though...
I agree the J-code swap may not make much noticeable difference on a higher mileage 6.2...worth the effort ?...maybe not..

I'm getting more and more discouraged with the 6.2's...tired of it not wanting to start when its below 25 degrees,killing batteries,despite good glow plugs and a gear reduction starter--its misfiring more now at idle,so I wouldn't doubt one or more cylinders are low on compression.

Twice in the past week I couldn't get my truck to start--even had two extra batteries wired in paralell with jumpers hooked to the two in the truck,and it still refused to spin over fast enough...
Good thing my life didn't depend on it to get me somewhere..

Next day, when it hit 40 degrees,it fired up on one turn of the crank..
I don't like having a vehicle I cant trust to start--especially once your far from home,and have no place to plug in a block heater or battery charger..

I have a line on a 80's 305 V8 out of a low mileage C-10 ,and a straight six out of a '72 Nova,for about 200-300 bucks each...tempted to buy them just to have,so when the 6.2 decides to make the big spit I will have another engine to put in ...

The diesel is nice for plowing IF you can get it started---the fuel injection and no spark plugs or wires to get wet and stall it are its best features,also fording deep puddles without fear...but in the long run I prefer a gas engine--they'll start regardless of temperature,and have more power,and your not limited to 3600 rpms too..

The "thrill" of having a noisy,smelly sluggish diesel wears thin pretty fast..at least for me it did..I'm also much more confident at repairing an old school small or big block or straight 6,the 6.2 is in a world of its own,and I'm not that fond of many of its designs..if I have to pull it out,I'm not putting another one back in...

 

[longbedder]

Meh, I can't kill my 6.2. It just friggin runs, and runs, and runs...pay attention to a few key service items and they give good service. Add a turbo and they run quite well, actually.

80's 305 V8 out of a low mileage C-10

Clearly we have different perspectives. IMO that's the biggest turd of an engine GM ever let out the door. I would not take a brand new one for free (my first truck was an '86 C-10 with a 305).

My 6.5 hauls my family with a load of Christmas gifts (going) or a couple dead deer (returning) halfway across the country in the dead of winter at 20 MPG. Not bad at all for a '94 Burb.

 

[diesel4me]

My pickup is used mostly to plow my driveway,go short distances to get groceries,to the dump to dispose of trash,maybe a flea market 25 miles away--and that's about it..don't really "need" a diesel for those chores...

I'd be more likely to trust it further from home if it was gas powered,like go to my sister or brothers house 70+ miles each way,or to concerts,but in its present state I wouldn't be surprised if the 6.2 decides to grenade soon..always sounds like it's ready to come apart..

The thing is lucky to get 16 mpg too,a gas engine wouldn't be much worse on fuel..truck also rides lousy,it weighs 6200 lbs and the front springs are about dead...its about as comfortable as a 10 wheeler on a long trip..but I would not be going far very often in it anyways..

Believe me I'm not a big fan of 305's either,but that is the only carbed V8 around here for cheap money...I'd actually take a straight six over the 305,they are pretty bullet proof and not much weaker as far as HP or torque..but getting scarce around here..

I'm on the fence whether to just take the pickup off the road and use it as a "yard truck" only,and start driving my '81 G-10 van again,or go through all the work of swapping a different engine in the pickup,replace the rotted inner fenders,and do a general "restoration" to it...
The van has sat a long time too though--still runs OK,but no doubt will need a lot of repairs if I try putting it back to use as a daily driver..brakes,steel lines,etc...and it sucks in snow..

My '85 K-10 Suburban with a 6.2 & 700R4 needs tranny work,and now the rockers and door bottoms have rotted on it--I'm tempted to just sell it ,with or without the Diamond plow setup I put on it,then never used it...if I could get more than I have in it,it would be gone already..
I feel stupid to have bought it in the first place--then let it sit & rot away--had big dreams when I first got it,then lost interest--.

...I'm getting to the age and health where doing major work to anything is not really possible,getting too old for that sh**..but I cannot afford to have it done for me either...stuck between a rock and a hard place--that is why I just keep patching and jerry-rigging things to keep them driveable instead of undertaking a task I may well be unable to finish...

 

[campfire]

Back to the o.p., you are confusing CDR with EGR. Crankcase depression lets air out of your crankcase. This is crucial so it doesn't build up pressure inside the crankcase and force oil out the seals (sound familiar?). All 6.x engines have this. The difference between c code and j code engines is the presence of exhaust gas recirculation. This dilutes your incoming air with exhaust to reduce NOx emissions. As you noted, j code engines block off these ports and skip egr altogether. You can disable egr easily by unplugging the solenoid (May as well unplug the EPR while you're at it), but the large vacuum diaphragm will still be blocking the intake airflow. These engines are starved for air anyways, so there is a benefit in switching to the unrestricted input.

 

[campfire]

Personally, I had a 6.5 intake lying around, so I used that instead of the j code intake. Unlike a gasser, the intake itself is optional. There's really nothing you can screw up. Injector line removal is not required for this job.

The 6.5 trucks run the CDR output into the turbine (which I do not have), so mine currently vents to atmosphere. Aside from this (which you won't have), my only side effects are a minor increase in power and a barely measurable decrease in fuel consumption. Nothing earth shattering. But aside from buying good glow plugs, this is the best mod I've done yet.

I have pictures at the beginning of my Suburban thread. Let me know if you have any questions.

Cheers!

 

[B.barket]

Back to the o.p., you are confusing CDR with EGR. Crankcase depression lets air out of your crankcase. This is crucial so it doesn't build up pressure inside the crankcase and force oil out the seals (sound familiar?). All 6.x engines have this. The difference between c code and j code engines is the presence of exhaust gas recirculation. This dilutes your incoming air with exhaust to reduce NOx emissions. As you noted, j code engines block off these ports and skip egr altogether. You can disable egr easily by unplugging the solenoid (May as well unplug the EPR while you're at it), but the large vacuum diaphragm will still be blocking the intake airflow. These engines are starved for air anyways, so there is a benefit in switching to the unrestricted input.

^^ crap!.. Thanks campfire.. Yes.. It's the EGR I mean to eliminate with the J code or possibly just block off on my C code.. not the CDR..

 

[campfire]

^^ crap!.. Thanks campfire.. Yes.. It's the EGR I mean to eliminate with the J code or possibly just block off on my C code.. not the CDR..

Getting rid of the air plug had a much more noticeable effect than simply unplugging it did. You also have an Exhaust Pressure Regulator that blocks off your driver-side exhaust manifold output when the cold idle solenoid is active. Blocking the exhaust forces exhaust into the EGR circuit, making the EGR more effective and the engine less effective. This is worth disconnecting, IMO. A factory J-code engine would not have had this "feature."

 

[diesel4me]

I deleted the EPR valve on my pickup--I swear it felt a bit more peppy with it gone...tempted to just remove the EGR valve and leave the intake on it and see if that helps any--its been un-plugged from the EGR solenoids since I got the truck..

 

[campfire]

I deleted the EPR valve on my pickup--I swear it felt a bit more peppy with it gone...tempted to just remove the EGR valve and leave the intake on it and see if that helps any--its been un-plugged from the EGR solenoids since I got the truck..

If you remove the valve without blocking off the port you will have a lot of extra exhaust recirculating all the time.