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6.2 about to go to scrap!

M

Menniss

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Location
San Diego
So Im so tired of throwing good money after bad. If I cant figure out this troubling issue the truck is going to the scrapper. So let me fill you all in.

It's an 84 CUCV. I replaced the motor almost 125k ago with a used Hmmv motor from ted's trucks. About 4 months ago I did the head gaskets, replaced the injectors, radiator, all hoses and glow plugs and cpr valve.
She was driving fine until about two weeks ago. I noticed she was running a little hot and checked my radiator fluid. it was very low and i topped it off. I looked over the motor to see as to where it could be coming from. No apparent leaks could be found.

BUT, I noticed milky film around the oil fill lip. removed the cap and there it was, crankcase back pressure. I checked the oil dipstick and found milky oil there too.

now Im not a diesel expert and started scratching my head. asking myself....what could it be? i crossed off head gasket as they were just done, no water out the exhaust and no extreme pressure on the radiator hoses.

So I took it to the guys who did my head gaskets. they immediately suspected my timing chain cover. So I agreed and let the work commence.
I picked the truck up on Friday and was in a hurry to get home before the storm. I failed to check for residual back pressure.

I drove the truck the Saturday to/from work. I noticed that she ran quieter and started easier. Sunday she didnt move and today I drove her around all day running errands. Late afternoon I noticed she was running a bit noisier, then I realized my feet werent warm. I immediately pulled over and checked the radiator. you guessed it....LOW! I topped her off and got my ass home. checked the oil fill and the pressure was back, oil milky.
I called the mechanic and he thinks its a bad block, most likely cracked. So tomorrow he is going to pull the oil pan, charge the cooling system and see if he can spot a water leak.

Do you all have any ideas as to what it might be? I love my truck and its my daily driver. I just cant afford to keep repairing it. nor do I have the time to do it myself.

Please advise.....
 
has a compression/leak down been done after the Hg replacement? did they use ARP or TTY? head could be warped or, bad block. why the timing chain cover? was it cracked when they showed it to you after the work? there is a steel backing plate between the cover and pump so i don't see how a leak could be there.
 
deejaaa said:
has a compression/leak down been done after the Hg replacement? did they use ARP or TTY? head could be warped or, bad block. why the timing chain cover? was it cracked when they showed it to you after the work? there is a steel backing plate between the cover and pump so i don't see how a leak could be there.
Click to expand...

The water pump ports go through the housing.

Drop the pan and look for leaks and or cracks.
 
but if it was the head gasket, wouldnt the radiator hoses get hard with the cap on? mine does not. you can pinch it with two fingers. remember I lack knowledge in the diesel realm.
 
forgot to mention. I have had a hard time finding a diesel mechanic in San Diego who will touch a 6.2. open to any suggestions.
 
Menniss said:
but if it was the head gasket, wouldnt the radiator hoses get hard with the cap on? mine does not. you can pinch it with two fingers. remember I lack knowledge in the diesel realm.
Click to expand...

Usually, dropping the pan is the only other thought I have right now.

I just went back to your original post. Does your engine oil have cooler lines running to the rad? Could be a leak in the rad if it does.
 
Now that you've found this site, you can do it yourself...

Sucks that your 6.2 has taken a leave.. Hopefully the water didn't steam away the lubricity of the oil and kill too many parts.

At idle the cooling system would seem normal. Under load things change quickly.

You've found the tell-tale signs of problems. Time to investigate.
 
NVW said:
I just went back to your original post. Does your engine oil have cooler lines running to the rad? Could be a leak in the rad if it does.
Click to expand...

Good thing to check. Even a trans cooler failure could throw oil (trans fluid) into the cooling system...
 
No time to do it myself. have a house remod going on and work 9-10 hours a day.

radiator- it does have an internal oil cooler. although it is new, I will check it out.

how does coolant get into the oil via the head gasket?

how does the excessive pressure get into the crankcase?
 
3500GMC said:
Good thing to check. Even a trans cooler failure could throw oil (trans fluid) into the cooling system...
Click to expand...
Actually what I was thinking was engine oil cooled by the rad. I have no idea if the OBS trucks did this. Just a WAG.
 
I was eluding to a trans cooler possibly being (also) a potential culprit.

Not 100% sure if both engine *and* trans coolers are stuffed in the radiator tanks....
 
well, we pulled the pan and pressurized the cooling system. as soon as we got to 18psi it started raining under the motor. cracked block. anyone know of a good reliable source for another 6.2?
 
Boyce equipment out of Utah. They pull the engines out of CCUV's and other military stuff with less than 30K on them. They then test run them on the stand. They have a 90 day warranty!

I have 2 engines from them and 30K on one.

They will run fine as is.

I would recommend that you put ARP head studs in with blue locktight on the block side of the studs, re-ring the engine with a light clean up on the cylinders. Gapless rings will keep your oil cleaner. But this is only a recommendation and not necessary.

http://www.boyceequipment.com/

Keep your IP, lines, and injectors from your other engine. Flush the engine oil cooler lines and cooler. If it is an air to air unit - replace it. Maybe have the radiator cleaned at a radiator shop. The goal is to clean out the oil coolers of water and oil mix and any debris as coolant wipes bearing real quick. You can not flush an air to oil cooler, this would look like a separate radiator in front of the main radiator.

Buy your mechanic a 6.2 diesel repair book. Ask questions here and make sure your mechanic is open to suggestions. Also local members can help you out some if you ask.
 
great tip! I contacted them today and they really worked with me. I ended up getting a low mileage 6.2 w/ a turbo. appreciate the help.
 
You will need a new Harmonic balancer on the front of the engine if yours is no good. The age appears to ruin the rubber in the surplus engines as well as use. This is a frequent maintenance item on our diesels. The dealer is a higher quality than dorman junk that you get at auto parts stores.
 
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