Help Diagnose '96 Frankenmotor, Low Power, w/ Torque Graphs

[rocketman]

Fairfax has good point as usual so if drop y pipe to see if guides have dropped down is important.

[aschwerin]

Ok, I'll try to do that.

 

Is there any scenario where I won't be removing the head?

[Fairtax4me]

I don't do the water test. I use diesel or kerosene. Not as thin as gasoline, but they still have a low surface tension so any imperfection in the valve seat they will seep through.

Gasoline can run through even the tiniest imperfection in the seat and can give a false indication.

 

Water has a high surface tension so a small imperfection it may not leak through, or if there is carbon or oil buildup on the valve or seat, it might not leak through.

Water works well enough of the valve is bent, or if it has a significant burn. A badly burned valve will show very low (under 30psi) or no compression though.

Partial/minor burn or an improperly cut seat or incorrectly lapped valve can still hold back water, but will show medium range compression when doing a compression test.

 

Remove the head, remove the valves from the head, and visually check the seats, valve faces, and measure the width of the contact area with the seat. IIRC the contact ring should be about 1.0-1.1mm. More will give a poor seal, less will cause the valve to burn.

[aschwerin]

OK

 

Should I necessarily do it myself instead of taking it to a different(!) machinist? I'm good at replacing parts but it gets a little iffier going into engine internals. But I can learn, if its unlikely I'll screw anything up...I just don't always have a clear picture how all those internals work together. Often when I do the work myself it takes much longer, but I often do a better job, and learn something too.

 

I may not have been clear with the leakdown test. The cylinder is not holding any pressure...the air gushes out as fast as it goes in from a good-sized air compressor (mostly through the exhaust valves). I can't see why anything else really matters until I find that valve problem. Unless I find something that tells me to junk the engine....

 

It might be a week until I get the head off. Thanks for all the tips.

[Fairtax4me]

Check out a few vids on the you tube on how to remove and install valves. Its not as hard as it might seem, but you do need a spring compressor. Craftsman sells one that's inexpensive and does work if you get it set up right.

I made one out of a pair of wide jaw vice grips with a big washer welded on the end.

 

The only thing to really watch out for is before you slide the valve out of the guide, feel around the groove of the stem for any burrs. Use emery cloth to get any burrs off before you remove the valve. Otherwise you can get the valve stuck in the guide and score the guide.

 

If air was obviously flying out of the exhaust valves, good chance one or both of them are burned. Maybe they weren't before, but it sounds like they are now.

[aschwerin]

 

 

[aschwerin]

With plug installed, diesel didn't drain through any valves. I put a washer over the exhaust port and applied compressed air. Much leakage through both #4 exhaust valves and the farther #2 ex valve.

 

Removed valves. They seem straight. I wouldn't say anything is burnt, but there is heavy carbon buildup on valves and seats. They cleaned up well, though some carbon was stuck on really hard. I used a braided wire wheel in an angle grinder for the valves, and cup wire wheel in drill for seats. Valve margins seem correct.

 

Besides checking a few other things in the manual, it seems the only other thing to do is check cam lobes and such for wear. Anything else before I put it back together?

[rocketman]

When you did compression ckeck,did you put oil in cylinder to see if compression was up? You may have bad rings or cam lobe.

[Fairtax4me]

Try lapping them for just a few turns and clean the compound off and see if the seats or valves have any uneven areas.

 

That inner exhaust valve on number two isn't running hot enough. There's fairly heavy buildup on that valve, but not on the others. Kinda seems like either the margin is too wide or the valve isn't opening far enough or maybe not at the correct time.

[aschwerin]

The contact ring [valve margins] measured closer to 1.2 mm, which is in spec with the Haynes manual. I'm quite pleased with the lapping job and resulting quality of valves. I ordered new valve stem seals. Still debating with myself if I want to invest in a micrometer to measure cam lobes. I can't see how valves not opening fully would significantly reduce my compression. 

 

The inner #2 exhaust valve had the best seal and I had thought for a little bit of not pulling it out. Glad I did now that I see how much cleaning I can do on the valves (and how easy it is). Maybe the HLA on that valve was compressed (or worn cam lobe). The margin was as fine as the others. All the valve heads seated real nice after lapping, using Prussian Blue.

[Fairtax4me]

I'm pretty well out of idears then... Unless the valve springs are toast or something.

Cam lobe worn enough to cause a valve opening problem should be pretty obvious.

[aschwerin]

OK, some development:

 

Today my valve stem oil seals are coming in the mail, and I was supposed to test everything (I bought a micrometer), reassemble, and test drive. I started with a "reverse compression" test by forcing air into the crankcase vent. And I found an error in my previous testing/comprehension:

 

When I was checking for leaks, I did not realize there was a passageway from crankcase through the heads. So I believe what I was feeling as valve leakage was just those passageways to the crankcase. And that explains really well why I did not have major valve issues. So plugging those passageways, there was clearly air leaking past the #4 piston. Nothing quantitative, but definitely not sealed well. I put some #00 grease around the edge of the piston and the air pushed its way through the grease, mostly right near the top of the piston. Although I couldn't identify any air pressure in cylinder #2, after #4 was greased, there were bubbles in #2 right at the bottom of the piston where a small oil puddle sat.

 

I think its a safe assumption that my #4 rings are bad? And #2 not great either. So...I have many questions...is the engine worth repairing? Why did the rings go bad? I'm not a hard driver, and only put 10,000 or so miles on the car, though it clearly ran better when I bought it. The hardest part was when I bought it in Milwaukee, and drove it down to Arkansas. When I stopped for gas in southern Illinois, I checked the oil and it was 2 quarts low. Either it was low when I bought the car or burned two quarts in one tank of gas. And of course its tendency to run low on oil since then, but never once did the oil light come on.

 

There's a guy nearby selling these engines for $200. That seems like a deal. He has 2.2's and 2.5's. As cool as the idea of the Frankenmotor seems, the 2.2 is a more reliable engine yes? I thought I heard things about rod bearing and such in the 2.5. I know from my 2.2 Sube that it has sufficient power for me, and I love how that engine keeps going and going. On the other hand, the 2.2L car has a body that is falling apart and I believe its going to need a clutch job soon.

 

Any thoughts on my situation?

[aschwerin]

Well the $200 engines are for "bad" engines that he had replaced. Which wouldn't get me any further than I am now. He also doesn't have any '95-'98 2.2L's, just the older ones.

[Svengouli7]

You could take the short block apart and get a better look at what's going on. If you have the time you may be able to re ring the short block, drop new bearings in it and do a quick lap job/table resurface on the heads. Doesn't sound like you have much to lose.

[Fairtax4me]

Probably the rings got wiped during the break-in and never had a chance.

You could pull the pistons out and just re-ring it. How do the cylinders look? Cross hatching still there? Any scoring?

[aschwerin]

Cross-hatching is visible in pictures. There might be scoring in the 1st picture? There are straight lines about where there is most leaking through the piston.

 

I thought I should try to find a cylinder bore gauge, and also re-hone the cylinders.

 

Also it seems I can check rod bearings after removing oil pan? I really don't hear any noise. I've got a friend whose Outback makes a knocking sound, and has for the last five years.

[Fairtax4me]

You can sort of check three of the rod bearings through the oil pan if you're creative. Block has to be split to check them all. The rods are assembled to the crank and the case halves put together around it. Pistons are then pushed into the block and the wrist pins inserted through access holes at the bottom of the bores.

 

If there is visible scoring of the cylinders a stone hone likely would not clean them up well enough. They would need to be re-bored and honed by a machinist.

Any sort of honing requires splitting the block anyway.

[GeneralDisorder]

That's a 96 25D block. With 2.2 heads the compression would be off the charts as evidenced by your insane compression numbers. You CANNOT run that engine without damaging the pistons.

 

The static compression ratio on that engine would be over 12:1. We tried building one of those years ago and even mixing in E85 it wouldn't stay out of detonation and melted the #4 piston.

 

#4 piston is melted or has shattered ring lands. Gauranteed.

 

You need 97-99 pistons to make that work.

 

The bores are probably fine. Some vertical scoring won't matter. Just drop in 97-99 pistons with new rings. DO NOT hone the cylinders. You will create an oil burning disaster.

 

GD

Edited February 28, 2017 by GeneralDisorder

[aschwerin]

Took a little bit until I could get back to this project, but pulled out the #4 piston just now. I'll post a couple pictures later, but looks like the a couple ring lands are busted up.

[GeneralDisorder]

Yep. Get some 97 to 99 pistons. That will drop your CR to about 10.6

[rocketman]

Yep,there you go,that's how we stick together here.

[aschwerin]

 

 

[aschwerin]

So my intention is not to do a full engine rebuild. The engine just isn't worth that much.... yet... the car is currently a backup car (driven a few times a month until the '97 Sube bites the dust), and both my wife and I drive conservatively.

 

- So I'd like to just replace the #4 piston and rings. Looking around for a bore gauge to borrow right now. There is that vertical scoring on the cylinder but it passes the "fingernail doesn't catch" test. Also, both #2 and #4 had some buildup on the top 1/4" or so...easily scraped off and that left like a 1/16" taper (wider bore) at the very top of the cylinder.

 

- Drop the oil pan and I know there is a piece I'm supposed to replace. Also feel (3) connecting rods for any play.

 

- Try to determine if clutch disc should be replaced, it looks like there is a lot of wear left. And pressure plate?? Hard to tell from the Haynes what constitutes "excessive wear". Rear main oil seal seems to show some leakage, and the bearing in the pressure plate seems to have a rough spot, so I'd replace those right now.

 

- I'll do a valve job and head gasket on the passenger side. Also might as well replace intake manifold gasket, and a couple small parts I broke taking things apart. A sensor (for the big hose that goes into the air assembly (IAC??)) has metal contact bits falling off the bottom. And replace exhaust manifold studs, quite thankful none of those broke.

Edited March 14, 2017 by aschwerin

[aschwerin]

Hmm, looks like it might be hard to find a single piston? Rockauto only has one option http://www.rockauto.com/en/moreinfo.php?pk=4800015&cc=1269985&jsn=380 , sold as a set of (4), and they look really cheap, or at least much different. Also only available on oversizes on Rockauto.

 

Maybe there's something on eBay

[GeneralDisorder]

You have to replace all 4. For one you can't buy those 96 specific pistons and for two the compression ratio IS TOO HIGH. It will just happen again. Trust me here - replacing that one piston is one going to result in serious frustration and more engine damage. Unless you have access to 140 octane leaded race fuel.

 

GD