what the hell happened to my motor!?

[infurno]

I finally did it. I ordered a bunch of parts, everything from head gaskets to new ford fuel injectors and even a new air boot.

Took it apart today, it was pretty easy. My first time and it took about 4 hours.

I expected to find it a mess but I never expected to find damage! :(

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[infurno]

A little bit of background...

The head was replaced about 2 years ago. It was bought rebuilt.

The car ran fine without any trouble for about 1 year. Then it started to smoke when starting.

Would only smoke when starting, not while driving.

I took the engine apart to make sure the head was ok, and to replace the valve seals. I was certain that was the problem.

[Jehu]

How's that cylinder wall look? The valve crumb get blown out the exhaust? All you need is a new Valve? That's not bad is it?

[infurno]

Just running my fingers over them in a circle its pretty smooth. Some have some light vertical scratches, maybe 4 or so sets on one I remember but not anything deep like a gorge.

[Jehu]

I have no idea what the reccomended protocol is for the next step but I gather new engines of this variety are neither very expensive nor very rare if you end up needing one.

[632 Regal]

your valve lash could have been set too tight not allowing the exhaust valves enough time to cool and they stuck in the guide and the pistons tapped them causing the busted crap. From the pics the block looks fine. New head time for sure at least but the scenerio goes like this. Engine runs although cylinders are dead creating an unusual force on the rod bearings... thus lower oil pressure and worn rod bearings. Soo... you could try swapping a head onto it or... probably for less money get a complete running engine and pop that in instead. The latter is what I would most likely choose.

Good luck with it, be glad it ran as transportation as long as it has.

[infurno]

When I first started I was really hoping that I could use the same head. I called around and a machine shop offered to replace my valve seals for $60.00.

If I bought a few new valves and had them readjusted is it possible that's all it would take to restore the motor?

Or is the head gone for sure?

That and a bit of work to clean out some of that carbon buildup.

[Paul in NZ]

what is the build up n the spark plug???

[Jehu]

what is the build up n the spark plug???


LOL>>.! looks like it blew lunch..

[Mordan]

Hello. I rebuilt my M20 head one month. I had a bent valve. and destroyed rocker arm. reason was: engine revved too high. First 2 pistons has some marks but the walls were smooth without marks.
I rebuilt the head, changed the exhaust vavle seats and guides (they are the weakest) and with the Goetze gasket and Elring studs, it cost me 650 euros.
I did it all myself so no other cost and it was a rewarding experience. I don't know in your area but a new M20 engine is 5000 euros and old ones in good shape are impossible to find. But then again my block was in good shape and there was no compression wave coming out of the oil cap. I have about 250k real kms and those 6 cylinders engine are sturdy. The head had already been rebuilt like yours.

What do you used as coolant? I don't see any rust in the coolant passages.

in your case I would replace the broken valve and check for cracks and check the guides and seats.

you already ordered parts. buying a new engine would make no sense.

[Ross]

Grind the gouges on the piston smooth, slap a used head on it and drive off.
I wouldn't worry about the lower end over this. Watch your valve lash as Regal says.

[Ferret]

Why didnt you pull the plugs before now, surely the state they're in would have given you a major warning about what was going on... as well as a compression test o.O

[infurno]

The plugs are only a few weeks old. I have known about this condition for a few months but university, work, weather and divine intervention got in the way.

As far as I knew I was just burning some oil when the car started so all I did was replace the plugs once they fail.

I did a compression test a few months back. My results were in the 180- 190. There is a thread about it here. The valve problem must be more recent.

I'm going to try just replacing the valves.

Anybody have any advice for how to clean out all that carbon? Is there anything that will dissolve it? I don't suppose a chisel and a hammer would be a good idea.

[whiskychaser]

Looks to me like you have more oil in there than a Somali pirate. My guess is min 2 valve guides are shot-seals wont do anything. Head could still be ok but I would suggest pressure test and new guides all round. As far as the bottom end is concerned, old school says get a new ring and measure the gap to see if its in spec. If not its rebore and oversize pistons and rings time. And if you have it on a bench you have got to check the big ends. If you dont fancy doing that in your back yard - and I have - then just take the lump out and put in one that works. If you calculate cost + time for each you will come to a pretty quick conclusion

[Paul in NZ]

looks To Me Like You Have More Oil In There Than A Somali Pirate.

:);)

[632 Regal]

all that crusty crap on the plugs is oil from the pistons free wheeling in the cylinders. valve guides are toasted from hitting the pistons so those would need replacement if the heads are not cracked.

[infurno]

Took the head to a machine shop today and the guy gave me a quote.

$475 to machine and rebuild the head, replace valve guides, damaged valves, ect.

I was hoping he could just patch it up enough to work through the rest of my time at the university and then I would deal with it then but he wont to do a patch job.

Im going to make some phone calls and see if I can get a good head for about $300-$450..

I already spent $400 on parts for this job, $450 more and I could have just bought an engine in the first place.

[infurno]

The guy there said that the reason the valves failed is because they were getting too thin from wear. Eventually they got so thin that they could not handle the heat and failed.

This explains why all the damage on the valves is on the same side as the spark plug.

He also said that the rest of the exhaust valves are probably in trouble too and should be replaced.

[Dave M]

Took the head to a machine shop today and the guy gave me a quote.

$475 to machine and rebuild the head, replace valve guides, damaged valves, ect.

I was hoping he could just patch it up enough to work through the rest of my time at the university and then I would deal with it then but he wont to do a patch job.

Im going to make some phone calls and see if I can get a good head for about $300-$450..

I already spent $400 on parts for this job, $450 more and I could have just bought an engine in the first place.

I'd pay MORE for your rebuilt head than another 'good' one. Whatever you pick up used may have cooties as well.

Dave

As long as they're using (assuming its not cracked)

[632 Regal]

Ahhh the old thinning valve trick... never heard of this.

[E34 530]

Hello. I rebuilt my M20 head one month. I had a bent valve. and destroyed rocker arm. reason was: engine revved too high. First 2 pistons has some marks but the walls were smooth without marks.
I rebuilt the head, changed the exhaust vavle seats and guides (they are the weakest) and with the Goetze gasket and Elring studs, it cost me 650 euros.
I did it all myself so no other cost and it was a rewarding experience. I don't know in your area but a new M20 engine is 5000 euros and old ones in good shape are impossible to find. But then again my block was in good shape and there was no compression wave coming out of the oil cap. I have about 250k real kms and those 6 cylinders engine are sturdy. The head had already been rebuilt like yours.

What do you used as coolant? I don't see any rust in the coolant passages.

in your case I would replace the broken valve and check for cracks and check the guides and seats.

you already ordered parts. buying a new engine would make no sense.

WTF, where are you that an M20 costs 5,000 euros?

[Jon K]

Valves dont get "thin" - they can get overheated and crack due to that, but they don't wear "thin"

[whiskychaser]

The guy there said that the reason the valves failed is because they were getting too thin from wear. Eventually they got so thin that they could not handle the heat and failed.
He also said that the rest of the exhaust valves are probably in trouble too and should be replaced.
Valve heads wear and you will find minimum thickness specs in Bentleys. You might want to have a look at this article regarding reasons for valve failure:
http://www.aa1car.com/library/ar1192.htm