6.2L Blues. . . lots of problems

[Vaughn MacKenzie]

I bought an old '84 Blazer a couple months ago and I finally got around to working on it a little and driving it around.

I changed the oil and did a few other things but it doesn't start worth a darn and the rear main seal leaks a lot.

This Blazer was parked for 7 years and only used to launch a boat. The owner always used starting fluid to get it going because the fuel system loses its prime when sitting.

The engine cranks over and will not fire when cold. Just rolls out clouds of white smoke. Checked glowplug relay and it's fine, there is power to all the plugs. Could it be all 8 are dead, or is my compression so bad it doesn't light off? I ordered a new set which I will install. So every morning I have to give it one quick squirt of ether and it lights off then it runs great.

The big problem is the rear main. Is it a job to change the seal? It leaks like a sieve. I lost 2 quarts of oil driving only 40 miles today, it got a lot worse. I have only driven it 125 miles since I started driving it and have used 3-4 quarts of oil since changing it.

Lastly what's up with the goofy blow-by contraption? It dumps it into the intake and it's loaded with a lot of crud. I hosed a lot of it down with carb cleaner, I had to do it slowly and carefully otherwise it detonated a lot.

Back to the blowby, it's a total volcano. . . tons of white vapor blowing at a high rate. About 5-10 times the amount of my high-mile Dodge Cummins. Is this motor pretty well used up at 161,000 miles? The exhaust smells absolutely sick, like a 2-cycle Detroit that burns a lot of oil.

Vaughn

[DmaxMaverick]

Your problems aren't as bad as they might seem.

Those glow plugs (all of them) are fried. Ether has a way of doing that. You'll need 8 of them. Good luck getting them out. Search previous posts for stuck glow plug procedures. Could get lucky.

The rear main is easy to replace. If you can get the pan off, it's a one afternoon shade tree job. Get a manual to help with that one if you've never done it.

That "blow-by" contraption is the CDR (Crankcase Depression Regulator). With those miles and age, replace it. It is probably the reason the rear main is blowing so much oil. Replace it BEFORE replacing the rear main. The best thing to do about all the crud in the intake is to take it off and have it hot tanked. Better yet, replace it with a non-EGR intake, like from a hummer. Ebay item.

I also suggest doing a couple short-term tranny services. If you have a 700r4, which it should, they are very sensitive to old oil and deposits. Use a pint of Trans-X or TransMedic with the "flushing" change to get the seals in shape. Don't use additives for the long haul.

If you don't know the injector history, a new set may be in your future. OEM's are not expensive. Don't worry about hi-pops until overhaul. If they are original, have them tested, or just put in a new set. 161K is a lot of miles on originals. Bad injectors can lead to other problems, like holey pistons.

Get all this stuff taken care of and you be in high cotton....for now. The exhaust smell should get back to normal. Watch your coolant levels and take it easy until it's in A-1 shape. Don't want to blow a head gasket. It may take a while of easy running to get that engine back into an everyday driver. Once you do, you should enjoy one of the stingiest oil burners you can get.

I could go on, but the questions will come up as you go along.

Good luck.

[catmandoo]

ya those g-plugs can be hell to get out,you might want to go to the 60g plugs,lots tougher then the originals.and watch where you go to test inj's the place i get my stuff from charges 16.00 per inj to test,so i said to heck with them and bought a pop tester off ebay ,and it's paid foritself 2 times over and i've only had it about 6 months.the only other thing i can say is check the oil sender switch too,it's on the back of the engine on the drivers side on top,this could be leaking too,

[Vaughn MacKenzie]

Excellent, thanks Maverick and Catmandoo!

I thought the rear main seal would require transmission removal. I have the mains girdle kit from Diesel Source or whoever it was so I could do both at the same time.

I am picking up the glowplugs today. . . no more ether for this beast. I think I will replace the injectors, no sense spending a lot to rework the originals. I am sure that would help the smoke and smell.

I could pick up a new breather valve but how about just running hose staight to the ground like the Cummins setup, and prevent blowing oil and stuff in there any longer?

Thanks again smile.gif

Vaughn

[DmaxMaverick]

I could pick up a new breather valve but how about just running hose staight to the ground like the Cummins setup, and prevent blowing oil and stuff in there any longer? I tried this on an '82. It was a mess! You will need some type of "catch can" in line with it somewhere to catch and condense the oil vapor and get it back into the crankcase. It didn't drip a lot, but would air brush the driveway a lot, even at idle.

I suggest replacing the CDR. It is designed to keep the crankcase at a slight vacuum under all conditions. This is important for rear main seal health. Your engine will likely have a high rate of blow-by and push a lot of oil vapor out of the vent.

I would also add that it would be a good idea to put a qt. of ATF in the engine oil for a couple hundred miles. It will help to free up things (like rings and lifters) inside the engine, which happens when they sit for long periods. Use a lighter viscosity oil for the first couple changes also, like 10W-30, CI rated. After that, use 15W-40.

What are your intentions with this truck? If you want to make a daily driver out of it, there are a few things you may want to do in addition. If all you want is a "beater", then you can forgo a lot.

[doncannon]

Hi Vaughn,
I just got done with my rear main and it was not as bad as I thought. The old rope came out easy and when I installed upper I got it half way in and then it stopped, so I pushed on it (easy) with a screw driver. You may want to put oil on so it goes in easier (remember with the lip fwd) and also when I did mine I found the screen off the oil pump (oops!). I got a new screen from a machine shop I should have just replaced the oil pump because of more problems. I replaced it and now I am back in business. Oh also you will need a torque wrench in inch pounds and one in foot pounds. All oil pan bolts are 84 inch pounds exept for the two rear are 17 foot pounds (10mm w/universal up front-timing cover, 10mm w/3 inch extension middle down the sides and 6inch for the ones where the oil pan drops down). The dipstick tube should tap out after you loosen the 10mm bolt on the dr side exhaust manifold (may need to work out with vise grip not too tight or tap them with a hammer). Oh the rear main is 110 inner and 100 fl-lbs outer. If you should need to take the oil pump loose it is 65 ft-lbs.
I hope this helps,
Good luck and let us know how it turns out,
Don

[Vaughn MacKenzie]

Well I'll replace the valve then and keep it set up as designed.

Don thanks for the instructions on the seal R&R. I will print it out for when I go do it.

Right now I parked it and am driving my '68 Cougar and working on finishing the valve job/head porting on my '96 Ram. Then I'll go after the Blazer.

I don't plan to use it as a daily driver but do want to make it roadworthy and will probably drive it in the winter quite a bit.

Thanks again you guys, you have been most helpful.

Vaughn

[Vaughn MacKenzie]

Well I have another thought, what if there is so much blowby it overwhelms the CDR valve?

I was visiting a friend over the weekend who also has a '84 Blazer. I pulled the lid off the air cleaner and started it and his rig has nowhere near the volume of vapor and airflow from the blowby that mine does. So I am thinking maybe I would be best off to vent the system to atmosphere and not run the risk of overpressure, or remove the valve and run the vent straight into the intake? How does the CDR work?

The more I mess with this thing the more I think it's pretty tired and worn out.

Vaughn

[JeepSJ]

Run it. It sat for 7 years, so the rings are probably stuck and the seals are dry. Change the oil and filter after about 500 miles and just keep running it and change the oil 500 miles after that. You can also try running some Marvel Mystery Oil mixed with the engine oil (wouldn't hurt to run it in your fuel also) to help get things loosened up.

[SimonUK]

If the CDR is used to create a vacuum in the oil pan then what do the guys that run turbos or the guys that have modified their air filter housings to increase airflow do to prevent the rear oil seal from leaking.

The reason I'm asking this is that i modified my spare air filter housing to allow maximum airflow to the filter and whilst the 6.2 runs a lot better(if a bit louder due to increased induction noise)the rear seal started leaking real bad.

Could be the seal is nearing the end of its life being an 84 with 60k miles on it (19k in the last 6 months)

I'm ordering a new seal on monday anyway but I'll fit the original air filter for now till it's replaced.

Simon.

[britannic]

On the turbo set up, the CDR is connected before the compressor, so that it it sees vacuum and not boost. The CDR also allows "metered" oil mist to lubricate the intake valves.


Originally posted by SimonUK:
If the CDR is used to create a vacuum in the oil pan then what do the guys that run turbos or the guys that have modified their air filter housings to increase airflow do to prevent the rear oil seal from leaking.

The reason I'm asking this is that i modified my spare air filter housing to allow maximum airflow to the filter and whilst the 6.2 runs a lot better(if a bit louder due to increased induction noise)the rear seal started leaking real bad.

Could be the seal is nearing the end of its life being an 84 with 60k miles on it (19k in the last 6 months)

I'm ordering a new seal on monday anyway but I'll fit the original air filter for now till it's replaced.

Simon.