6.2L J code - blowby -rebuild time?

[ApocBane]

Hello,

First please forgive my mechanical knowledge short comings. I've been learning as I go.

I have a 1986 K5 with a 6.2L J code Diesel.

Recent replacements.
1. Rear main seal
2. Oil pan/seal
3. New CDR valve

Engine Behavior - Idles and run's good, just burns oil, 1/4 quart 100-200 miles.

Problem.
Engine continues to burn oil, as evident by blowby smoking out of oil fillcap/breather and oil dipstick.

Can you please suggest the next step?
1. Rebuild (if so how much should I expect to pay)
2. New engine
3. Some thing else I can investigate to narrow the problem down?


Thank you for your time and assistance I do appreciate it.

[ApocBane]

After reading some more threads.

Further possibilities
1. Injection pump, but engine runs/idles good. No problems starting.
2. Advance engine timing, I'll have to check that. Due to timing chain being loose from time.
3.Noted someone suggested changing oil from rotella to something synthetic. Another said add Marvel Mystery Oil.
4. Have compression check done.

[Edahall]

Also, check your CDR valve. The CDR is very similar to a PCV valve on a gas engine and if this device has somehow failed, you might see higher oil consumption.

Here's a good article that explains how to diagnose:
http://blog.heathdiesel.com/2006/04/cdr-crankcase-depression-regulator.html

Are you using an engine oil made for diesels like Delo 400 or Shell Rotella?

[ApocBane]

Thanks for the response.

I bought a new CDR valve and installed it, but this doesn't rule out the possibility of the new one not being good. I'll try the water test to see if does what it's supposed to.

I usually use the Delo 400, this last time it was Rotella. I added some engine cleaners, so next oil change 200-500, I'll get a better oil in there.
I also bought a diesel compression tester, so I'll be doing that as well.


I bought new Kennedy plugs but the connectors on the engine are too narrow to fit on the Kennedy plug. Looks like I'll have to rewire all of the connectors =( Does anyone know a part number or place for the connectors I need to rewire the truck?

[Edahall]

Delo 400 is good oil.

What type of driving is this vehicle used for? Lots of idling and in town driving would increase oil consumption. Do you get blue smoke out of the exhaust when you punch it?

You could also file down the plugs so it fits your existing connectors.

[ApocBane]

You could also file down the plugs so it fits your existing connectors.

That's a good idea.

Really I haven't been driving it all too much do to maintenance issues. I bought it about a year ago and have been working on it steady. Was leaking oil and transmission fluid. I replaced the rear main, a new oil pan and seal, seemed to fix the oil leak. New tranny pan and seal, fixed the transmission leak. hmmm
I did notice a lot of oil sitting in the valley under the intake manifold. I cleaned it with a rag the best I could, but wasn't sure where it could have been blown out of.

When I do drive it's on rainy days when the hog stays in the garage. It's used to commute about 30 miles.

When I punch it hard I do believe there is smoke. Not sure if it's blue or black. Ill give it a good punch on the way home to check.

[ApocBane]

I bought the 25 dollar harbor freight compression test. I can't seem to test the passenger side because the adapter is too short and when I try to attach the gauge side connector, it hits the exhaust manifold and won't attach.

I got the drivers side done

Firewall
305
405
380
395

Seems to fail the 80% - lowest can be 324? no?

Is it alright to loosen the exhaust manifold on the passenger side to do the test?

[Edahall]

You can loosen the exhaust manifold. If you get good numbers on the other side, I wonder if either your valve guides could be bad or your oil rings could be getting worn out. If that's so, you have several choices. You could just drive it the way it is and keep adding oil. Your engine is probably turning that oil into power anyways. Then you could install a Franz filter and never have to change oil. Or you could go and rebuild that engine. How many miles does the engine have on it?

[ApocBane]

I appreciate your responses.

I managed to check all but one of the cylinders compression.

firewall passenger
--
305-310
395
410

firewall driver
305-310
405
380
395

Looks like 2 for sure are acting up.

I decided to install the new glow plugs, top off the oil, and continue driving.

I've started calling around for shops to do the rebuild. One crazy shop said 6-7k, another said around 3k. Waiting to hear back from another.

Couple tried to sell me on a waste of time rebuilding a 6.2, as it is powerless. I think it does the right job for me. Good MPG, and good enough power, I'm not towing anything =)

One shop tried to tell me the 6.2 wasn't designed to be a diesel in the first place. Which I know is incorrect, as Detroit Diesel designed it as a diesel.

The alternative is sell it as is for a low price. Shopping for anything that is 4x4 with diesel is effin expensive though.

[DmaxMaverick]

Cylinders 7 and 8 compression will be significantly lower than the others (typically). This is one reason the engine must be up to operating temperature during a compression test (a real PITA, to be sure, but necessary for reliable results). Your compression numbers seem right in line with what I see on a cold-warm engine, when the compression is acceptable at full operating temp.

[ApocBane]

Cylinders 7 and 8 compression will be significantly lower than the others (typically). This is one reason the engine must be up to operating temperature during a compression test (a real PITA, to be sure, but necessary for reliable results). Your compression numbers seem right in line with what I see on a cold-warm engine, when the compression is acceptable at full operating temp.

Good point, the test was done cold.

Does this mean you're leaning away from rebuild, or just that compression is ok?

It burns a lot of oil, otherwise ok.

[DmaxMaverick]

Your compression may be low in those cylinders, but you can't be sure unless the test is done correctly. If you do it at operating temperature, and they are still below spec, then it's time for rebuild. On the other hand, it's a Diesel, and burns oil, so no harm from that alone. You'll have to weigh all the factors, and decide what's in your best interest. If your only symptom is increased oil consumption, there are other ways to "help" the condition. You may try other oil brands, to start with. Higher consumption is typical when you change brands often. Find a good one, and stay with it. If you've used an engine cleaner oil additive, give that a chance to work. It may be a simple as stuck rings, which wouldn't be that uncommon, especially in the back cylinders.

If it runs well and has no other problems, I might be inclined to run it as-is, and just monitor the trends for other changes. Take the time to find or build a good replacement, for when it does become necessary.

[ApocBane]

Thank you for the sound advice, I appreciate it.

Edahall suggest Delo, which oil do you prefer.

I tried this engine supplement
http://www.barsproducts.com/1000.htm

Do you have one you prefer or suggest?

Thanks.

I broke the guage on the cheaper harbor freight compression test, so I'll have to buy another kit to do the warm test.