How long before rebuilt engine rings seat? EDIT. Help a 1st time engine builder.

[brianao34]

I had totally missed this thread before but after reading a few threads I'm saying valve seals. But are the valve seals even there to leak that much oil!?! wow

I totally rebuilt my S50 and it never smoked. I'm also one of those let it warm up and drive it hard (within reason) folks. Best of luck, hope you find a quick/easy/cheap(relatively) fix with this. I have my fingers crossed for you.

Thanks man. Yea, it sucks but it is my first top to bottom rebuild so there were just too many variables to be flawless.

[e30rapidic]

I had totally missed this thread before but after reading a few threads I'm saying valve seals. But are the valve seals even there to leak that much oil!?! wow

I totally rebuilt my S50 and it never smoked. I'm also one of those let it warm up and drive it hard (within reason) folks. Best of luck, hope you find a quick/easy/cheap(relatively) fix with this. I have my fingers crossed for you.

[brianao34]

A compression and leak down tests are essentially a test of the compression rings and the valves. The compression rings can seal even though the oil control rings have never seated, which is typically the result of a failure to cross hatch hone the cylinders or cylinders that are worn past the wear limit. Excessive oil burning can also be from worn valve guides and/or bad valve seals.

Yea, I've heard that before, I'm thinking I'm just going to replace the valve seals before I tear the engine completely apart and hope for the best.

I've seen bad valve seals kill an m52 by burning up all the oil within a 175 mile trip, left full of oil, arrived and at destination very unhappy and siezed going up the driveway that's when it was discovered it burnt away all of its oil. This was on an engine that although was completely refreshed not rebuilt, sat for 4-5 months before it was put in the car and the valve seals dried out. Something to think about

That's a good point, the head did sit dry for probably 6 months before I had a chance to put the engine together. That sounds very feasible. Thanks.

[SmokeE30]

I've seen bad valve seals kill an m52 by burning up all the oil within a 175 mile trip, left full of oil, arrived and at destination very unhappy and siezed going up the driveway that's when it was discovered it burnt away all of its oil. This was on an engine that although was completely refreshed not rebuilt, sat for 4-5 months before it was put in the car and the valve seals dried out. Something to think about

[whodwho]

Unless I missed it, when do you notice it smokes?

You should be able to narrow it down by:
on accel - rings
on decel - stem seals
when leaving a light after idling - stem seals

5 qts of oil in 75 mi it should be smoking like a freight train if it is burning it!

[TobyB]

ANd Harbor Freight is for things like hammers and pry bars,

not leakdown testers and torque wrenches!

t

[jlevie]

A compression and leak down tests are essentially a test of the compression rings and the valves. The compression rings can seal even though the oil control rings have never seated, which is typically the result of a failure to cross hatch hone the cylinders or cylinders that are worn past the wear limit. Excessive oil burning can also be from worn valve guides and/or bad valve seals.

[brianao34]

UPDATE
So I got a nice OTC cylinder leakdown tester for Christmas and retested my engine after warming it to operating temperature...
Everything was 5% or less! WOOOP! Giant sigh of relief.
So that just leaves the valve stem seals, and if it's loosing oil that fast it'd have to be something drastic like the machinist forgot a few...
:)

[brianao34]

Well, after reading online about how inaccurate the Harbor Freight Leakdown tester is I feel a lot better, and it only tests at 15psi...

The project is on hold for now until I get moved into my new house at the end of the month, but I WILL be updated with a solution.

For now I'm just hoping the machinist that "went through" the head screwed up the valves seals or something simple.

[TobyB]

Yar, new motor <10% with Deves, <5% total seal.

...and a leakdown test isn't going to show up bad valve stem seals no matter....

I think the cylinder with 30% needs a borescope, and hope it's not a pin- meets- wall event.

t

[ForcedFirebird]

30% is a lot.

If you had the pistons at TDC and the air was escaping from the oil dipstick, the rings are toast in that cylinder.

[brianao34]

Sorry to be the bearer of bad news, but that means the air is escaping into the crank case - usually means rings or a damaged piston.

Yea, I know, but you're always going to have leakage past the rings. And I forgot that the engine was dead cold when I did the test :/ oops.

[ForcedFirebird]

Yea, I'm almost sure it's got to be valve seals and possibly guides after reading around and talking to that guy. Because the engine pulls really hard and I have no smoke at idle.

And I should have mentioned before, when I did the leakdown, the only place I could hear air escaping was through the oil filler cap/dipstick.

Sorry to be the bearer of bad news, but that means the air is escaping into the crank case - usually means rings or a damaged piston.

[brianao34]

You could try doing a dry compression check, then add a little oil into each cylinder. If the number comes up, its rings, if it stays the same, the issue is in the head. With the leakdown, you should be able to hear where the air is escaping to. Its hard to pinpoint sometimes however.

Will

Yea, I'm almost sure it's got to be valve seals and possibly guides after reading around and talking to that guy. Because the engine pulls really hard and I have no smoke at idle.

And I should have mentioned before, when I did the leakdown, the only place I could hear air escaping was through the oil filler cap/dipstick.

[BlackbirdM3]

You could try doing a dry compression check, then add a little oil into each cylinder. If the number comes up, its rings, if it stays the same, the issue is in the head. With the leakdown, you should be able to hear where the air is escaping to. Its hard to pinpoint sometimes however.

Will