6.5 Turbo Question

396 TransAm · Oct 3, 2023

I need someone's opinion on a potential truck purchase. I found a guy with a 93 3500 4x4 6.5 Turbo with 114k miles on it. He said that it runs and drives great. When I went to look at it yesterday that was not the case. He said that he had just run up the road with it to put some fuel in it. When I started it up it took about 20 seconds for it to fire up (started hard for being warm already). Idles nice and sounds good, BUT it starts missing very badly when you rev it about 3k and blows white smoke like crazy. No smoke or miss when it is idling. My question is could he have got some bad fuel (full of water)? Would that cause this? He did say that the gas station where he got the fuel had just re-opened the Diesel pump and that it had been down for about three months.
I really want this truck but I am afraid that maybe there is a bigger problem here. Any help would be greatly appreciated.

Barrman · Oct 3, 2023

1993 should be the mechanical DB2 injection pump. That means the drivability issues shouldn’t be electronic.

The engine should start in less than 2 or 3 seconds of cranking hot or cold after a glow plug cycle. Reasons for a warmed up engine to require an extended crank time normally is the injection pump needing a rebuild. There should be enough fuel in the IP to let it run 30-180 seconds with no fuel getting supplied.

White smoke above 3,000 rpm makes me think head gaskets or cracked head/ cracked block. That one really is a puzzler.

Here is a video I did about running an IP dry and then bleeding it to running again. Near the beginning of the video you will hear a warmed up engine start for comparison:

396 TransAm · Oct 3, 2023

Ok, thanks for the info. So you think it is definitely more than just water in the fuel ?

Barrman · Oct 3, 2023

I have installed a water injection set up on my GEP 6500 with a Banks turbo. At full flow and 2500 rpm I get no smoke of any kind out the tail pipe. To me, there has to be a lot of water in the mix for it to be visible out the tail pipe. I would suggest checking coolant level, pull the radiator cap with the engine running and look for bubbles and if possible doing a coolant system pressure test. Hot and cold engine if possible.

CT-BLAZER · Oct 3, 2023

The white smoke is a sign of gloom and doom! !
Seller is not telling you everything he knows......

Head gasgets, cracked heads, block .... God only knows , till it's ripped down +!internals are inspected.

Your looking at thousands in repairs.... Upwards of replacing the engine. Last re power was $10K , in 2009.

The starting issue could be fuel injection, glow plug issues, or just coolant in the cylinders....

That trucks interior & exterior would have to be in new condition, before I would consider evaluating it's value as a none runner......or whole sale value minus $10K for repairs

This truck sounds like it's a candidate for the salvage yard

The above posts have sound advice.

I'd run .... run. .... run. ... Away from this truck.

ZooMad75 · Oct 3, 2023

The fact it had a 6.5 would have had me running even before the attempted start up.

Then hearing about the hard start and poor running with smoke, yeah no. Pass on that turd.

396 TransAm · Oct 4, 2023

Ok, thanks for the advice guys. Running away as advised.

2INSANE · Oct 8, 2023

Even if it sat for 3 months, it should not smoke like crazy.

Here’s what I would do…

I would ask the seller to let you do a compression test on all 8 cylinders. If he does let you do a compression test and all the cylinder compression numbers turn out fine, I would buy it and do further testing on it.

Most likely if the compression is good, it’s going to be IP, Injectors or turbo.

Was he asking a lot of green for it?

396 TransAm · Oct 9, 2023

3K, I was buying it for the engine only. I need it for a super clean '94 Dually that I ran across with a popped 6.5T. Everyone wants me to put a gasser in it, but I don't want to mess with the harness.

Chickntrk · Oct 9, 2023

The harness is nothing compared to the issues running a 6.5 will give you IMO. Buy a whole junk truck and use the harness from it, scrap the rest.

396 TransAm · Oct 9, 2023

I was reading on the 8.1 swap. There is a lot of good stuff on it here. Doesn't seem to be a lot of them out there though (at least local to me).

2INSANE · Oct 10, 2023

396 TransAm said:
3K, I was buying it for the engine only. I need it for a super clean '94 Dually that I ran across with a popped 6.5T. Everyone wants me to put a gasser in it, but I don't want to mess with the harness.

If all you need is the motor at $3000… I would rather use that $3000 and buy 3 online auction 6.5 diesel Optimizer takeouts on Govplanet.com

This would give you a much better block and you would have 2 left over blocks you could easily clean up and sell for $2000 each not including any parts to the block.

Barrman · Oct 10, 2023

I second the GEP 6500 Optimizer suggestion. No, the center mount turbo won’t fit in a square body easily. But those engines can take a side mount turbo just fine.

eodcoduto · Oct 17, 2023

Where is anyone finding optimizer engines for $1000!?

2INSANE · Oct 21, 2023

eodcoduto said:
Where is anyone finding optimizer engines for $1000!?

They pop up on govplanet.com from time to time. You could get them less then $1000 sometimes but they may need to be rebuilt because they sit outside on pallets exposed to the weather causing the piston rings to rust in the cylinders.

CT-BLAZER · Oct 21, 2023

Yes, but don't forget buyers fee's, crating charges loading ,& shipping fees State Taxes .... online buying has extra surprises .

In an unseen engine. Scary thought

396 TransAm · Oct 23, 2023

So, I found a 93 3500HD ambulance with 43K on it. The guy was asking 3,500 and settled for 2,700. It runs and sounds great. Only thing is this:
After about 15 mins the temp gauge pegs suddenly and it overheats. As soon as you open the vent/bleed valve on the stat housing it spews steam for about 5 seconds and it immediately cools to 150 degrees and will stay running without getting hot the rest of the day. It only does it after complete cool down. I suspect one of the two issues:

#1 -- PO changed the water pump as it was weeping. I suspect an air pocket in the system. The ambulance has rear heat and the plumbing is ran all crazy to the rear heat exchanger. I think that the pocket works it way up to the stat housing (the highest point in the system) and gets stuck there. Could there be a way that after it cools down it is sucking in air? Note, this thing has a coolant housing on the firewall and the radiator has no filler neck, which sucks.

#2 -- PO told me that he suspected a possible head gasket blown and charging the coolant system. I disagree with this as the engine would still continue to overheat with the continuous combustion chamber charge into the system.

Thoughts ???

Barrman · Oct 23, 2023

Is the thermostat really the highest point in the system? If not, there might even be a bleed valve somewhere.

The ambulance might have the dual serpentine belt alternator installed. Very handy to have that.

2INSANE · Oct 23, 2023

Sounds like a bad thermostat or a thermostat installed backwards.

If you suspect bad head gaskets, do a compression test or coolant pressure test.

2INSANE · Oct 26, 2023

Some Optimizers on auction just popped up. Would have to swap heads if you wanted a side mount turbo. Even if you just bought one for only the block, it would be worth bidding at least $1500 I think… You could use your current 6.5 parts to make one badass Optimizer for cheap.

Out of all of these motors, I think I would rather shoot for this 6.2 that looks brand new, put 18:1 pistons, girdle, main studs, head studs, Fluidamper and turbo it.

GM 6.2L Diesel Engine

Used surplus Engine in Capac, Michigan, United States for sale, inspected and guaranteed. null

www.govplanet.com

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