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Rear main seal blowing out


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jonathancecil97
Novice

Apr 17, 2017, 3:34 PM

Post #1 of 19 (297 views)
Rear main seal blowing out Sign In

Hey everybody, I'm new to the site and quite frankly running out of ideas on what this issue I'm having could be. Thanks in advance for the help. I have a 2007 Chevy Trailblazer SS, 6.0L 364ci. It has 130,000 miles on it but I recently put a rebuilt motor with unknown miles, in it because the last motor blew up due to oil loss/starvation. I got the new motor in and it seems to run fine except it blew out the rear main seal, I had it replaced and within less than 500 miles it blew out again (repair shop replaced entire housing). So this leads me to believe it could have something to do with crankcase pressure. I'm open to other ideas as well, just let me know what you guys think it is and where I should start to diagnose/fix it. I'm not sure if this issue could be what made me lose all of the oil in the first engine or not, unfortunately I didn't even check to see where the oil leaked from in the old engine. It was already knocking by the time I realized I had no oil. The current motor was rebuilt, when I bought it, it came with refurbished heads, and already had a new oil pump installed, other than that I basically had to transfer all of the other components from the old motor to the new. I hoope this is enough info, thanks again guys.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 17, 2017, 4:00 PM

Post #2 of 19 (288 views)
Re: Rear main seal blowing out Sign In

Check the PCV pipe and fittings for any restrictions.






~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kev2
Veteran
kev2 profile image

Apr 17, 2017, 4:01 PM

Post #3 of 19 (286 views)
Re: Rear main seal blowing out Sign In

first thought is a problem with engine block breathing AKA PCV venting...
Other things to consider
Excess compression blow by.
Engine is STOCK? Have you checked crank thrust?
Manual trans ? let us know
The crank was ground or polished where it could be undercut affecting seal diameter? VERY unlikely


jonathancecil97
Novice

Apr 17, 2017, 4:14 PM

Post #4 of 19 (276 views)
Re: Rear main seal blowing out Sign In

Yes, engine is 100% stock, with the exception of a k&n air filter, which doesn't really count. It's an automatic, and haven't checked the crankshaft play, no.


kev2
Veteran
kev2 profile image

Apr 17, 2017, 4:17 PM

Post #5 of 19 (274 views)
Re: Rear main seal blowing out Sign In

Is the seal suspected due to oil? If so did you check TSB's - ther are some for this - srrry cannot attach them tonight


jonathancecil97
Novice

Apr 17, 2017, 4:20 PM

Post #6 of 19 (274 views)
Re: Rear main seal blowing out Sign In

I also have oil burning off the passenger side exhaust manifold, there don't seem to be signs of oil coming out of the valve cover, but I replaced the seal anyway to see if that is where the oil was getting onto the manifold, but oil is still leaking onto the manifold from somewhere. The oil on the exhaust manifold obviously smokes and definitely smokes more under acceleration.


jonathancecil97
Novice

Apr 17, 2017, 4:22 PM

Post #7 of 19 (272 views)
Re: Rear main seal blowing out Sign In

I haven't checked the tsbs, honestly don't know where to look for them at. When you have some free time, would you attach them to the thread for me?


jonathancecil97
Novice

Apr 17, 2017, 4:26 PM

Post #8 of 19 (270 views)
Re: Rear main seal blowing out Sign In

In the picture shown above, that hose has lots suction on the valve cover side of it, so I assume that means there are no blockages. I have heard that you should feel some suction in the oil fill cap when you remove it, but there is none.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 17, 2017, 4:44 PM

Post #9 of 19 (260 views)
Re: Rear main seal blowing out Sign In

Check that it's not plugged within the valve cover



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jonathancecil97
Novice

Apr 17, 2017, 4:45 PM

Post #10 of 19 (256 views)
Re: Rear main seal blowing out Sign In

The valve cover is brand new


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 18, 2017, 12:29 AM

Post #11 of 19 (217 views)
Re: Rear main seal blowing out Sign In

Quote that might matter ">Yes, engine is 100% stock, with the exception of a k&n air filter, which doesn't really count.<"


If just a replacement OE filter fine. If that changed the air intake parts design it totally counts and can only cause extra problems if not a cause of current problems so strongly suggest getting rid of that. If trickery worked for real better anything about it, it would be the OE design from GM,


T



kev2
Veteran
kev2 profile image

Apr 18, 2017, 5:57 AM

Post #12 of 19 (203 views)
Re: Rear main seal blowing out Sign In

what is the indicators that the rear main seal is bad?
Is there an oil leak and assume its rear main?
TSB's I will try to add numbers later I have to search for them,
A thought - engine running remove oil fill cap place hand there - vacuum or compression?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 18, 2017, 6:15 AM

Post #13 of 19 (193 views)
Re: Rear main seal blowing out Sign In

Right Kev2 is crankcase vacuum or pressure. Problem here as quick look at many possible K&N air filter engine destroyers showed this..........

Great. It gives you an elbow to rig up for filtered air return to crankcase for what PCV system took out. Perhaps it's adding pressure by location instead or screwed up air intake in its intended way or plain hooked up to something incorrect?


IDK - but there's nothing good about altering this. Can it (corrected typo) pressure up to leak out oil - yes. Weakest spot first might not be seen but oil would quickly contaminate if that happens as the blow-by fumes are all around.


This would be more possible cause of a problem not likely to fix it getting rid of it now but wouldn't hurt to try. Once engine if it can run under vacuum in crankcase leak should stop if real lucky,


T



(This post was edited by Tom Greenleaf on Apr 18, 2017, 6:34 AM)


jonathancecil97
Novice

Apr 18, 2017, 6:18 AM

Post #14 of 19 (191 views)
Re: Rear main seal blowing out Sign In

Oil is pouring out of the bellhousing behind the starter, the starter is covered in oil, as is the entire passenger side of the frame all the way to the rear bumper. I had the rear main seal replaced, and the leak was fixed, but reappeared less than 500 miles later. It can lose 5 quarts of oil just by being driven around for one day. And before you ask, the oil sending unit is not leaking, the valley cover is not leaking, the oil pan gasket is not leaking, and the oil filter is not leaking either.


jonathancecil97
Novice

Apr 18, 2017, 6:27 AM

Post #15 of 19 (189 views)
Re: Rear main seal blowing out Sign In

Look Tom, I know you're trying to help, but I can assure you, me replacing my airfilter didn't cause a major leak like this, you're confused. And your replies are extremely difficult to understand, your sentences don't make any sense.


jonathancecil97
Novice

Apr 18, 2017, 6:29 AM

Post #16 of 19 (185 views)
Re: Rear main seal blowing out Sign In

And kev2, when it's running, there is no suction on the oil fill cap, I stated that above in one of the replies and no suction seems a bit odd to me.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 18, 2017, 6:42 AM

Post #17 of 19 (178 views)
Re: Rear main seal blowing out Sign In

Sorry for confusion and just corrected a typo that would confuse. The point is for any reason, the crankcase area of an engine is supposed to be under a very slight vacuum you could measure. That's why removing oil cap to see was suggested. I would prefer using the dipstick tube and do for check out vehicles.


If that blows OUT something is wrong but not known what so fast.
What lack of venting out the fumes does is ruin the oil then in turn not a good lubricant anything needs. It's just a POSSIBLE reason for this much done to this engine. Maybe not.


It's both an opinion and witnessed that replacing a rear main when known the problem doesn't work a very high percent of the tries. That's because it probably has too much crankshaft motion out of spec and beats new seal back and just leaks again. It's classic for that.


Most would do that in super high miles, low quality oil and or not changed enough and throw in a problem ignored or not noticed that wrecks oiling,


T



kev2
Veteran
kev2 profile image

Apr 18, 2017, 7:12 AM

Post #18 of 19 (169 views)
Re: Rear main seal blowing out Sign In

I cannot attach the document - will try to summarize - you will need to confirm your RPO's for applicable or not... your friendly GM dealer or any professional repair facility should have access OR maybe google.
TSB -
05-06-01-034F Porous block, sealing rear cover,
07-06- 01-004 oil pressure switch leak,
05-06-01-022B oil leak crank CHECK RPO! not sure this applies
Will add anymore time permitting


kev2
Veteran
kev2 profile image

Apr 18, 2017, 11:05 AM

Post #19 of 19 (149 views)
Re: Rear main seal blowing out Sign In

A quick thought - the PCV hose on valve cover have you tried blowing into and drawing air out? the baffle inside should be open no restrictions....too simple to not mention.






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