How long does it take to rebuild and engine?
 

Hi Guys,

My lovely car just went in for a cylinder leak test and returned the following results:

Cylinder 1: 28
Cylinder 2: 22
Cylinder 3: 25
Cylinder 4: 26
Cylinder 5: 20
Cylinder 6: 18

So I have 3 options, 1)get a shop the rebuild it, 2) rebuild it myself or 3) sell it.

I've discounted option 1 on the basis of cost, so I'd like to know how long it would take approximately to strip the engine but NOT split the case and rebuild it from thier.

I have the technology and I have Wayne's book, but I don't have a lot of time, hopefully option 3 won't come into play!

Why do you need to rebuild?

Are there specific issues?

While not new specs, the results are not terrible.

Where are the leaks?

What is your compression?

You may be able to keep you car on the road and keep your money in your pocket for quite a while.

I would have the leakdown test redone by another shop. The numbers are too close in value; I would not have expected them to all go down simultaneously. I question if the procedure was done properly or if there was loose carbon keeping valves from seating.

Provided you have the parts on hand (you may need new pistons and cylinders), probably machine shop "turn around time" for the heads is the controlling factor. If this is not a factor, and you can apply yourself, the engine could be rebuilt in two weeks if nothing goes wrong.

Jim

Re-read chapter 1 - the leakdown test is only one test - it should not be used alone to evaluate your engine's condition. Do some of the other tests featured in Chapter One...

-Wayne

Thanks Guys,

I'll get some more diagnostics done and re-read the book before I rip it apart.

The guy at the shop said it was leaking around the rings and the valves, he was all doom and gloom saying that if I leave it much longer it could be terminal!

What would I do without you guys? Spend a lot more money that's what!

Thanks!

Well, as I mentioned in the book, your mechanic has a vested interest ($$$) in seeing you rebuild your engine. If need be, take it to a 2nd guy for an eval, letting him know that he's doing an eval only...

-Wayne

And make the shop one that has no relationship with your original mechanic. People do talk...

did the test get done when the engine was hot, so the rings are oiled? cold leakdowns are inaccurate. the engine also needs to be run after the plugs have been loosened a 1/2 turn, to blow out carbon bits loosened by plug removal, that might be sandwiched between valve and seat. any cylinders with high readings should be retested after running the engine again.

I've just had the second test done, I stood over the guy when he did to ensure it was done correctly and got the folloing results:

Cylinder 1: 19
Cylinder 2: 21
Cylinder 3: 18
Cylinder 4: 21
Cylinder 5: 16
Cylinder 6: 15

All much nicer numbers! Looks like there's life in the old girl yet!

I plan to rebuild the engine enyway in a year or so, but now at least I have time to start saving for a rebuild and maybe S cams, new pistons, koni suspension, MSD, uprated brakes............

Thanks guys

What are the compression numbers, and how much oil is it consuming?

-Wayne

Wayne,

oil is not being consumed at a noticeable rate (all leaks have been cured) and it doesn't seem to go down much at all.

I don't have compression figures at the moment

You need to keep track of how much oil is being used, and also do a compression test. Read this:

http://www.pelicanparts.com/techarticles/mult_Engine_Rebuild/mult_engine_rebuild-1.htm

-Wayne

Thanks Wayne!

Just a quick update,

Compression test has been carried out and everything came out fine, cylinders were no more than 11% off the highest value.

Looks like there's life in the old girl yet!

Moral of the story, always get a second opinion, and ALWAYS read Wayne's book first!

With numbers like you have and a shop telling you doom and gloom, RUN, don't walk, to another mechanic, and consider never going back to the first.

Unless you are racing it and are running first place most of the time you will never know the difference, its in 100ths of seconds per 2 mile lap. Sort of like changing engines every race.

Whatever you do...don't go to Motormeister for anything to do with anything regarding your engine. Simply put....i was drug through a knot hole and after 7 months am finally getting my engine put back together. Use a good local machine shop for all you machine work. Dissasembly and reassembly is really not very hard if you have the right tools. QUICK TIP...goto Sears and get the ratchet wrenches and the pivot head sockets. They are a must for a rebuild. And dont hessitate to spend the $75 or so for a cam holder tool.

I'm not sure I'd go back to that shop to be honest with you...

For a non-case split rebuild, I've done it twice, can really get it done in a weekend, probably 25-30 hours of labor. This doesn't include machine work, etc.. which will add to the chronological time of the rebuild, but I see abso. no reason to dig into yours with those numbers.

Re: How long does it take to rebuild and engine?
 

I'm gonna feel like an idiot for saying this (heck, I'm used to that); are these numbers % leakdown? And if they are, am I the only
one who thinks 28% leakdown is pretty bad? Please tell me you just left out the decimal points...
-Chris

You know that saying "There are no stupid questions"? Well we're going to make an exception in your case Chris.

bump

I'm with Chris, I have a stupid question to ask....Uhm, please see Chris' post...

I agree with you also Chris, I had an engine with 40% & 25% cylinders, and when we tore it down, they were scored pretty bad. But I am tired of defending leakdown tests over compression test.

Whooo, there is a BIG difference between 28% and 40% leakdown. 28% may be ok, but 40% is BAD. If your worst leak is like the numbers you have, ie 28% worst case, your engine is ok. Unless you are racing for first place wait until your numbers hit something like 35% or more.

By the way the simple compression test of an engine with 28% leakdown and 40% leakdown are likely to be the same. So what does that prove? In fact I just tore down an engine with perfactly good compression numbers that had all broken compression rings! It did, however fail leakdown at something like 40% to 60% numbers. The compression numbers were all 150 plus or minus 5 lbs.

Hmm, 5% leakdown would be ideal. I tend to think anything past 10% is cause for concern. Again, it's only one test - and needs to be considered in conjunction with the others.

Your engine won't self-destruct if the rings are worn - it will just lose a lot of power...

-Wayne

Some of the leakdown testers come with a good, questionable, bad zone printed along with the leakage number. The typical "bad" is 60% or more, good usually extends to 35 or 40%, with the yellow questionable inbetween.

A lot depends on WHY the leakage is high. If, for example, its the valves, and only the valves, with other info to back it up, then a valve job is indicated, and not a complete overhall.

I doubt most cars would show less than 10% leakage. Typical numbers I have seen on BMWs(325, 633, 635, M6(before rebuild), DKW, Porsche(1600,2.2,3.0), VW,MG, Metropolitan, 283, 327, 409, 440, 318, 361, Sunbeam, Kaiser, Jeep, AMC, and several I have completely forgotten about, even a Falcone and DeSoto, when they were running ok ranged between 7% to 30%. There was ALWAYS huge leakdowns, ie 60% or more when there were broken rings. Almost all the ones with broken rings PASSED the compression check test.

Anyway one thing I have noticed is that a good leakdown test can be touchy, ie hard to get good numbers, unless you are very careful to do everything right. I have noticed that a motor with 5% leakdowns can have 15 to30% leakdowns if not up to operating temp, if there is a little carbon build up on the valves, or if the piston isn't in the correct position. Thats my 02 cents worth from some of the cars I have owned.

Chris,

Yes this was %age leakage, and yes 28% is a bit high, but I had a second test done and the figures were lower, as such everything is cool and the gang!

Luke

Luke,

Noticed your in London, where abouts, there seem to be a few of us posting here from the Uk.

Who did those tests by the way.

Saw your purple car pics, very nice.

Cheers,

Michel.

Michel, I've private messaged you.

Luke