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Engine woes already

Black Thunder

Well-known member
Oct 14, 2001
Port St Lucie,FL
1968 Black Custom Vert 454 BB
Have oil dripping from side pipe:(
Did a compression check all are OK. One cylinder has oil wet plug. Is it possible a bad valve guide could cause this much oil to get into exhaust?
There's a couple of things that will cause it. Have you had the heads off or put different ones on or changed rockers? Some months back I posted a topic with a situation that drove me and some engine builders NUTS!!! To make a long story short, I replaced my stock heads with Trick Flo aluminum heads and when I installed them I never noticed the intake rocker stud is drilled all the way through in to the port. I never used thread sealer on the rocker studs and as a result I had a major smoke and oil consumption problem and it took many hours of brain racking and testing to find it. Pulled the intake studs, sealed them up and the problem went away. I was using a quart to 100 miles and the smoke was real bad. A simple over sight that caused me many hours of frustration. Let us know what you find out, good luck.
Keith my first reaction was that it was a ring but cylinder with oil wet plug is showing almost 150 lbs. Certainly thats to high for a broken ring.

It started when I was dialing in Holley. I was about to try a run under power & noticed it leaking oil out side pipe as I was getting in.

My heart sank & sure enough as I drove the smoke was bad. Car runs out fine , no miss just oil getting into exhaust.

Never owned a motor that is this extensively gone through. It has TRW pistons with chrome rings. I changed over to synthetic oil about a week prior to this happening. Used Mobil 1 15-50.

Engine has been together for a few years so something like Rowdy encountered could be ruled out hopefully. I am probably dreaming to think a valve guide could leak this badly.

Thanks for input as I am not up on things like I was years ago.
New Holley, new gasket on old Holley strip dominator manifold. Better not trash my motor changing oils:mad
Its going in tomorrow to a local mechanic that works only on Corvettes. Had to wait a week to get in, so theirs alot of Vettes here.
Prepared for the worst but hoping for the best!
Thanks for the input:beer
As I read the symptoms, they are:
Compression test ok
oil leaking out the exhaust
visible smoke from exhaust
one plug wet with oil
new engine

I'd start by checking the to make sure the valve stem seals on that cylinder were properly installed. If you verify the seals as ok, then, check for an oil leak from the valley into the intake port for that cylinder. If that's not it, considering the quantity of oil is enough to leak out the exhast, I'd be looking at either a broken or improperly installed oil ring on that cylinder.

I noted mention of chrome rings--they're highly unusual these days, especially on street cars. They are not desireable becaue of an inordinately long time required for ring seating. Typically, you don't see chrome rings in high-performance applications other than those that involve significant amounts of dirt and dust in the engine.
Black Thunder, This may be way out in left field but, what transmission do you have ? Auto or stanard? And which plug/plugs are wet????????Steve
Keith....Manifold never disturbed. Replaced old 850 Holley as previous owner admittted to what he called alot of tweaking & could not get idle settled down, so started fresh with new 800 Holley.

Hib....This engine has been together for a few years. Was originally set up for drag racing and was extensively gone through & previous owner stated that it had chrome rings. Agree totally that not the rings to use on a street application. Can only hope problem lies in valve seal area. After reading some old BBFH articles this weekend I am really feeling envious,, 12 sec,125+ quarter mile times. Ohhh myyy Goddd!!!!

Steve....Fairly new Ramchargers Auto TH400 w/3500 stall & cooler. Plug is last cylinder drivers side against firewall, IE the hardest to get at...hehe!
Was great talking to you on phone & send my tush holders ASAP!

Thanks for your thoughts guys, appreciate your time.... John
OK, as I said this may be a "stretch" but, it happened to me once. I had a brand new GM engine that I put in a 79 Blazer, it ran great but after a while it began to smoke like crazy. Having a real good waranty, I took the truck to Chevy, they called me in about an hour and said my truck was done and that I owed them $100.00, or so. Come to find out there wasn't anything wrong with the motor, it was a bad modulator valve on the transmision. It was sucking transmision fluid into the intake. Who woulda thunk? However it was burning most of it on the passenger side. you might remove the vacuum line going to the trans just to see what happens............BTW.........Tush holders are boxed and waiting for UPS..........Tush Holders :D ............Steve
Keith.....I am becoming increasingly bothered by my switch to synthetic. Will go back to good old gummy oil. Actually idle still sucks which was kinda disheartening after purchasing a brand spanking new (Silver plated edition) Holley. Idle will trail off & had to compensate by raising idle. Planned on letting the local guru give it all a through look over. Its hard to give it up when its new to the driveway. Was spending a little time trying to dial in new carb as float levels were off. Thats when oil dripping started, & after a short ride with smoke pouring out, drove home & parked it. Took it to the local guru after work today & ride across town was embarassing with smoke pouring out:eyerole

Steve.....Glad I made you smile. Am sure the installed T/holders will certainly make me smile. Will relay about possible modulator problems. Thanks for telling your story.

You guys have been super & I really thank you all. Its been a very, very long time since my last Vette & this one is really unique & hope problems settle down so I can just enjoy it!

Keith......Did check bolts holding intake & found a couple had to be retorqued slightly. Did not do a vacuum test. Since its in the shop this mystery will soon be solved. If its rings, I'm in for alot of work. May the gods be kind!!!!!!!!.......John
Keith....Ty again for # & your time!......John
The oil type is not your problem.

One thing I don't recall being listed was if this engine has exhibited this oil control problem since new/freshly overhauled or was it ok for some period of time then started loosing oil.
Black Thunder said:

Can only hope problem lies in valve seal area. After reading some old BBFH articles this weekend I am really feeling envious,, 12 sec,125+ quarter mile times. Ohhh myyy Goddd!!!!

Actually, the car has gone quicker than that. It went 11.97 right after the six-speed was put in. Unfortunately, the old BBfH has fallen on hard times. Vette Magazine Editor, Bob Wallace, has decided to kill the project. He reasoning was that, since he'd been Editor, he'd not gotten any mail about the project.

The car will "live-on" on the Internet and, as something other than the BBfH, in other magazine articles.

In a recent chassis dyno test the car didn't perform that well most likely because of tired valve springs. In the interim, I have new springs coming. Shortly after than we're looking at modern aluminum heads and a more aggressive camshaft.
Hib......My experience with this motor is only 3 weeks old. No doubt that it has miles & is suffering from wear & tear. The oil problem came out of nowhere. I was resigned to the fact that I had never felt the engines potential but it was acceptable to me. But events like the oil leak must be fixed immediately.
Even a tired 468 cu motor is a thrill for me. Sorry to hear BBFH is being sidelined for it represents what us older guys feel is, & always will be the ultimate. A BIG BLOCK bas ass Corvette!
I have followed your writing for a very long time Hib & respect greatly your advice. I sincerely thank you for your time!.....John
vac mod valve

I simply wish to attest to what Steve has already suggested ... that the motor could be sucking tranny fluid up through a bad vac mod valve ... I've personally had this happen ... albeit not on a vette.
...one other test

Boy we all love this diagnosis stuff don't we.
One fast check you can do for the intake gasket is to spray starting fluid around the intake while the engine is running. If the idle goes up (try not to get any near the air cleaner) then you have a leak.
have a fire extingusher handy
don't do it on a hot engine
look at the engine at night to see if there is any spark arcing.

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