Massive oil leak through intake.. not your average blow by.

I just got back from a long trip in my XJ lightly documented here:
http://www.naxja.org/forum/showthread.php?t=947544

1990 XJ 200,000 miles approx.

Our Jeeps are notorious for small amounts of blow by, but nothing i have ever seen or read about that is like this..

On my way back from Kansas, i was towing a fully loaded 4'x8' Uhaul trailer. Of course driving up-hill was harder then usual, and the engine was strained more. Fortunately no over heating, no loss in oil pressure no other problems but this...

I lost about a total of 2 quarts of oil out the intake. Once i noticed the problem, i tried to monitor when it would happen. It seemed to happen when i was going up hills trying to at least maintain the speed limit with the gas pedal almost to the floor, if not to the floor. RPM's between 4000 and 5000. (5000 is redline on my RENIX)

I'm not sure what is causing this, that's why i need your guys expertise.

These are the things i have thought to be the culprit:

1.) When i changed the oil pan gasket again before this trip, i also installed a new oil pump. I was thinking maybe the oil pump was not bleeding off the excess pressure. Seems very unlikely, but its part of my thought process.

2.) The CCV tube that runs from the intake manifold to the rear of the valve cover (closest to the firewall) has a 90 degree piece of molded rubber that connects to the hard plastic hose that goes to the valve cover. This 90 degree piece seems flimsy. Its not cracked or anything, but its soft and seems like it could be possible that its collapsing under vacuum, if that is even possible that it could be? Its a very short section of rubber, so i don't know if its even possible for that to happen??

3.) Piston rings are going bad?

The rest of the CCV system is perfect. The metered orifice is clean, and the valve cover is super clean on the inside as i cleaned it really really well when i had it off about a month ago. This oil loss has never been an issue until now, and i wont know if it continues to be a problem until i drive it more this next week when i go back to work.

Any suggestions, ideas etc would be greatly appreciated.

Thanks for your time.

I have some rough blow by till i ran some seafoam through the head and injectors cleared it out with a huge cloud of smoke blow by is almost all gone. may try it an see if it is reduced any. 2 quarts is alot though

XJ Stryker said:

I have some rough blow by till i ran some seafoam through the head and injectors cleared it out with a huge cloud of smoke blow by is almost all gone. may try it an see if it is reduced any. 2 quarts is alot though

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Ive done that, and ive had the head off about 2 months ago to replace a exhaust manifold stud. Everything was super clean and looked good.

The CCV tube that runs from the intake manifold to the rear of the valve cover (closest to the firewall) . Pull that hose off and try to blow through it , if you cant , spray some brake cleaner or carb cleaner through it . If that line is plugged it will fill your air box with oil at high RPMs and will cause alot pressure in the valve cover causing your oil cap to leak oil and run to the back of the firewall . Worked for me , Good luck .

REPOXP777 said:

The CCV tube that runs from the intake manifold to the rear of the valve cover (closest to the firewall) . Pull that hose off and try to blow through it , if you cant , spray some brake cleaner or carb cleaner through it . If that line is plugged it will fill your air box with oil at high RPMs and will cause alot pressure in the valve cover causing your oil cap to leak oil and run to the back of the firewall . Worked for me , Good luck .

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Yes ive read about blowby before and ive tried that. Its not clogged. For shits and giggles when i first noticed this problem in Denver, i sprayed carb cleaner through the hose. It came out the other end just fine, and looked clean.

Time for a cly leak down test. Rings are probably leaking.

bics90xj said:

Time for a cly leak down test. Rings are probably leaking.

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Could you eloborate?

How is this test performed etc?

It's a compression test. When you do a test, you pull a spark plug, and put a compression tester in place. Disco coil so it don't start, crank a few times and check to see what it built up to. The tester I used had a button that would release the pressure off the gauge. I just made sure I was still on a sealed stroke (under pressure and valves closed) and hold button and watch to see how fast it drops. Couldn't say that is the correct way to do it.

Do a vacuum test first, that can tell you just as much. But, only if you know what your looking for. It will help determine if your valve seals/guides are worn. If it passes that test, then try a compression test. I would be supprised if the rings are worn that bad.

clean everything in the CCV out and run it under "normal" conditions for a couple days to see if it continues. Remember that the CCV needs relatively strong vacuum to operate correctly and at 4000-5000 RPM pulling a hill with a trailor, you're not creating much vacuum. You could, very well, have just been pumping more oil to the top end than the CCV system could cope with at less than normal vacuum.

BillBraski said:

Do a vacuum test first, that can tell you just as much. But, only if you know what your looking for. It will help determine if your valve seals/guides are worn. If it passes that test, then try a compression test. I would be supprised if the rings are worn that bad.

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This procedure should be outlined in my FSM correct?

Shorty said:

clean everything in the CCV out and run it under "normal" conditions for a couple days to see if it continues. Remember that the CCV needs relatively strong vacuum to operate correctly and at 4000-5000 RPM pulling a hill with a trailor, you're not creating much vacuum. You could, very well, have just been pumping more oil to the top end than the CCV system could cope with at less than normal vacuum.

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Very interesting. Ive never thought about it like that. What kind of fix could i do for something like that then? I mean almost 2 quarts is alot of oil at 5-6$ a quart!.

Oh the CCV system was and is clean.

http://findarticles.com/p/articles/mi_qa3828/is_200108/ai_n8978956
FindArticles - Reading a vacuum gauge

A good guide for doing the vacuum test.

stop pulling hills at WOT with a trailor!!:roflmao:

I'm not sure what the "cure" would be, but maybe a baffle in the valve cover that would restrict the reverse flow of oil better. If you find something that works, don't keep it a secret though!

Well today i drove it for awhile running around town, and absoloutly no blowby like before ... and i even pushed it a little bit. Everything is exactly as it was before we left. Plenty of power etc..

More input?

maybe a Chrysler one way check valve for the air inlet side that would restrict the reverse flow of oil to the air cleaner box. I tried fitting one under the hood without much luck, but it could be installed at the box without any major problems.

the idea is to stop the reverse flow of oil to the air box without stopping airflow to the valve cover under normal conditions

Purolator B43132 breather filter/cap should work as the check valve.

The solution is to realize that you have an XJ with 200K on it and that it's not new anymore.

When you plopped the pedal to the wood to try and make these hills at speed (What? 75mph?), you increased your blowby and dropped your vacuum. In short, your CCV system stopped working and started dumping oil out the valve cover breather.

You do know to tow in "3" and not "D" right?
Also, let your XJ slow on hills, it won't hurt anything not to do the speed limit and it will prevent problems.

Other than that, you have a 200K mile that you ran for 29 hours. What did you expect, it made it didn't it?

Ron

Zuki-Ron said:

The solution is to realize that you have an XJ with 200K on it and that it's not new anymore.

When you plopped the pedal to the wood to try and make these hills at speed (What? 75mph?), you increased your blowby and dropped your vacuum. In short, your CCV system stopped working and started dumping oil out the valve cover breather.

You do know to tow in "3" and not "D" right?
Also, let your XJ slow on hills, it won't hurt anything not to do the speed limit and it will prevent problems.

Other than that, you have a 200K mile that you ran for 29 hours. What did you expect, it made it didn't it?

Ron

Click to expand...

Maybe i just needed a reality check! Thanks... and yes i know i tow in 3rd.

Ya my 87 will do that on long high speed trips. Sucks

mikeNtucson said:

It's a compression test. When you do a test, you pull a spark plug, and put a compression tester in place. Disco coil so it don't start, crank a few times and check to see what it built up to. The tester I used had a button that would release the pressure off the gauge. I just made sure I was still on a sealed stroke (under pressure and valves closed) and hold button and watch to see how fast it drops. Couldn't say that is the correct way to do it.

Click to expand...

Just to clarify:A leak down test is different than a compression test.a leak down test measures how well your rings and valves are sealing.A compression test essentially does the same thing,though.

I replaced line to airbox with 5/8 coolant line straight from V/C to airbox.
Used a big soup can as a catch with copper dish scrubber as a filter held in place with a couple of baffles.
A bolt in the bottom as a drain for regular maint. all held together by good ol JB