My engine has been diagnosed with excessive crankcase pressure due to blow-by. Mechanic says the rings are shot and I need to have mine re-built or get a new engine. I guess my question is to you guys is...1) how long can I drive it like this...(its not smoking) and 2) is there any thing else I should ask the mechanic to look at that could cause the pressure? I guess I'm hoping that there is some obscure $5.00 part that could be causing this that no one ever thinks to look at.
The car only has 95,000 miles on it. Mechanic says that it is unusual for the rings to go under 150,000 miles. Says someone must not have changed the oil in it for a period of time.

Any comments/suggestions would be most welcome! :seeya

 

This is where some snake oils actually become a viable option. If you have no other choice than a rebuild (could always get a second opinion), you could try something like Restore. What year is your vette?

 

Its a 1991. Shop said not to put any additives in it. They put an older model year EGR valve in it, so it will open up sooner to let the pressure off. The car had blown 2 intake manifold seals trying to release the pressure. I'm almost tempted to sell it to some unsuspecting person, since it was done to me, but I'm really not that kind of person. Ahhh, the joys of vette ownership! :cry

 

Ladyinblack, I may be wrong, but the PCV valve is supposed to allow the crankcase pressure to vent. Have you changed this yet? :flag

 

Thanks for the reply....maybe it was the PCV valve that he replaced, and not the EGR...I was so upset when I got the phone call, I just zoned out. I've been driving it gently, but I'm afraid to go far in it. Will it go all at once, or give some indication first that its on it's last legs? :cry

 

You may not need a new engine. Ask the mechanic what the compression is in all of the 8 cylinders and write it down.

All it may need is a new piston or even just a new set of rings on one piston.

If a one truck owner had this problem he would do as I said and then drop the pan, replace the pistons and put in a new set of main bearings. This would take a weekend to do. He would be driving it Monday morning.


[Modified by Don Martin, 10:43 AM 11/25/2001]

 

If this was my truck or I was going to sell the car, then I'd do exactly that, but if you plan on keeping the car, you might as well pull the engine and do it right. I agree with the not using addititive stance the shop has except for Restore. Yes, it is a band-aid, but it's worth a try, only because in your circumstances, you really have nothing to loose. I've never heard of anyone stating that this particular product causing any damage. You might have to resort to an open breather to help vent the excess pressure.

 

Thanks, Don....I was actually thinking of that...so it is possible that only one piston could be affected? Would that cause the manifold seal to blow? Oil was also coming out of the dipstick tube.

 

Thanks Romeo....ahhhh, decisions, decisions....rebuild mine 1/2 way or all the way....or, new short block or long block....or a new re-built one....or drive it until it dies????? All this thinking could drive a person to drink....I wonder if it will make it to the bar and back? :lol: :cheers:

 

A cheap way around it is to just put in new rings. If your engine is in pretty good shape it will work. The heads have to come off, along with the oil pan. The block can stay in the car. The cylinders can be honed without removing the motor. No more machining necessary- minimal cost to fix your problem. :smash:

 

ladyinblack....you seem to have some serious blow by going on with oil blowing out of the dipstick and intake gaskets blowing out..........my suggestion depends on how much you like you r vette....if you like it except this failure, have a bsic rebuild done at a reputable engine shop.......figure another $2,000 to get it done.......I know an excellent shop here in Iowa that will do it for 2 grand with R&R and all.........an exchange engine will run you more........probably a lot more :(
Good luck!! let us know what you decide.....

 

It's possible we're missing something here, so I'd ask you to backup just a bit. Does the motor consume oil and at what rate? Does it leak much and any idea where from? If you pull the oil fill cap with it running do you see vapor coming out? If you seat the dipstick and drive the car, does it blow out? Does the car run okay? Do the plugs foul up?

I've had some rigs that used a fair amount of oil and none of them ever did the things like you describe of blowing out intake gaskets. I'd figure if the rings are so shot the PCV can't keep up the car would smoke like a mosquito fogger, load up the plugs and generally run like a dog.

Rings are among the items I would think would be the last to go on a SBC, long after the cam (poor power) and the bearings (low oil pressure).

That said, there are other things which can cause the excess pressure and still leave the car running decent. Specifically headgaskets. When my GN was my driver, I raced it for a season with a leaking gasket (running mid 12s) before it let go. It's a lot easier and neater to change a headgasket or two than doing a rebuild.

I know you plan to keep the car, but it's a real shame to open the motor up and not "improve" things with a cam/heads and such, so I'd advise more research and a 2nd opinion before pulling the motor, spending a lot of $$$ and ending up with no more performance than you had. Like others said before, cut out the mechanics "spin" and ask for the numbers from a compression and/or leakdown test.

Mark

 

Lady i Black: I can relate strongly to this dilema. I checked will 3 local corvette specialists, and one far away (Vette DR). The rebuild option varied alot, and they would not commit to an exact price. When I asked for a replacement engine, I was told there are none left. But they all reccomended the ZZ4 as a good start with some of my original equipment. The off the road timeframe from all was months. Now I have a very drivaeable corvette, with alot of performance options that really don't make it to much faster than it was originally. First get a second opinon, then Take it a reliable mechanic that stands behind his work, and has replaced a C4 engine at least once. The more aftermarket items you put on, the higher the cost and they don't always fit (without costly modifications). I chose to replace all sensors, and new water pump, and new hoses. My cheap neighbor would have just reringed the motor and put fresh gaskets on. My way cost $14K with new trans and all the labor and aftermarket goodies. That includes the ZZ4 block. Choices. Would have been cheaper to buy a different low milage same year car, if transportation was the only deciding factor.
Cheers,
Christopher

 

A buddy of mine just put new rings in his blazer and it helped a lot-- he didnt have compression in 2 cylinders-- could try this first?

 

I agree with vanduker.

Make sure you have a new PCV valve. Then check these things:

1. How is the oil consumption ?

2. Does it put out blue smoke when you accelerate ?

3. Any oil coming out of the dipstick ?

4. You might want to get a compression check too by a different mechanic. Tell him to give the you number for each cylinder.

I had an engine that had a piston with a cracked head that smoked, consumed oil like gas, put oil out throught the breather and pushed the dipstick an inch out of the tube. The intake seals never got damaged from this problem.

The mileage on the car seems to low for the rings to be worn out unless something else has damaged the pistons or rings.


[Modified by AquaMetallic94LT1, 9:13 PM 11/25/2001]

 

Minimal cost my butt... unless you're doing this yourself the labor costs run up very quickly!!!!

I know I had a problem of about the magnitude, labor hours wise it was nearly identical to have them do a swap as it was to have the heads machined / gaskets fixed.

 

I can relate to feelin duped...

2 months after I got mine it blew head gaskets & warped 2 heads during emissions testing.... you can imagine that I failed the test ;P I had to force it home.

Labor costs for the head work & gaskets was about $50 cheaper as an estimate then a full engine swap which he gave me a flat rate on ($900, he does all our families work and has done good work before).

So I dropped $2800 on a new engine, should be finished with it this month, and then on to tuning and continuing the restoration.

Yes I feel screwed over having bought this 'Vette, but I loved the 2 months I got to drive it, look at it this way: a corvette is like a stripper... great fun with the seat of the pants feel... but you're paying a ton of coin per minute that could be hard for much cheaper elsewhere... but you really enjoy this one ;)

 

Someone needs to explain this one to me. First off, EGR does not operate at idle and startup (and WOT too). There is an EGR solenoid that distributes manifold vacuum to the EGR valve, that keeps it from operating until parameters in the ECM are met. If the solenoid was shot, then I suppose that it could be leaking manifold vacuum to the valve, but the valve itself and the rate at which it acts shouldn't have been changed. Sounds to me like your mechanic is blowing smoke up your bum.

I know Bills86Coupe has written a few good in's and out's on EGR in some past posts. Might wanna breeze through them real quick.

 

Ladyinblack, I know that you are exploring which way to go with your car. I understand that Jaspers engine and trans. is big on the East coast and may be an option for you. I've been trying to get some feedback from anyone that has Jaspers more locally and has used them. You see I need to replace my motor and the best offer so far has been from them. They will rebuild my motor (longblock) for $2005.00 with a 75,000 mile 36 month warrentte.
If you or anyone else has heard anything about Jaspers, please let me know.
Here is their webpage:http://www.jasperengines.com/frames.html
Thanks and good luck!!!

 

If it turns out to be something more than and easy fix don't rebuild, its a pain in the butt, I have done it several times. Get a GM Crate engine. You'll wind up spending just as much anyhow, and with the crate you have some assurances.