I wasn't sure whether to put this in the Performance and Maintenance section or not, but whatever-here goes.

Apparently I am one of only 3-4 people in the world to have a catastrophic failure of a 1UZ-FE engine in my '97 SC400 with ~180,000mi.

Here is the background: I had a coolant leak,which I found to be coming from the water manifold that contains the thermostat housing. I replaced the o-ring on the neck part, installed a gasket on the square opening, and installed a new thermostat gasket, new spark plugs. Topped off the coolant, bled the system-all good.
Took the car for a test drive, three miles up the road, turned around headed back home. Car was running perfectly. Made it to within 300' of my driveway, running at a steady 2650 rpm (70mph) when the engine just shut down. I coasted to the side of the road, put it in neutral and tried to start. The engine spun slower than normal, bucked and made a clunking noise as it turned over.

A friend helped me tow it home, and put it on the lift. Tried starting again with same results. Dropped oil pan and windage tray- no chunks! Removed left side plugs- no coolant or discoloration.
I put a socket and breaker bar on the crank nut and turned the motor by hand. It turned for most of a rotation but then stopped dead as if something was wedged. The timing belt is not broken ( I replaced the belt, water pump, idlers, tensioner about three years ago-it ran perfectly.).

That's as far as I've gotten, but from everything I know about motors, it looks like I may have dropped a valve!

I am about to go and get a used '96 engine out of an LS400 from wrecking yard, but before I do that does anyone have any other suggestions or possibilities to consider?

Regards,
M.R.

 

Well, it's looking more and more like a dropped/bent valve! I decided not to buy the used motor until I am sure of what the problem is. I pulled the exhaust cams and loosened the caps on the intakes, and now I can rotate the crank past the point that it was stuck previously. I pulled the shim buckets on the exhaust valves and tried to pull the valves and springs ou. Nothing budged so I guess there was no keeper failure. The intakes are going to take more work.
The adventure continues tomorrow. I'm going to try and remove one or both cylinder heads to get a better look.

Anybody got a good cylinder head and one piston / rod assembly they wanna sell

Stay tuned boys n' girls...

Regards,
M.R.

 

Hello Boys n' Girls it's your ol' pal again, with s***y news from the engine bay.
I disassembled the front of the engine, removed the timing belt, removed the exhaust cams, and loosened the intakes so all valves were in the closed position. There was no evidence of cam shaft journal seizure.

The crank now spins without binding. I then installed my compression tester hose in each cylinder in turn. All the driver side cylinders showed no sign of leakage through the valves, and only slight leakage past the rings into the crank case.

However-on the passenger side #8, #6 & #2 all leaked air profusely through the intake. So I guess I was right, unfortunately.
My guess is that the timing belt slipped and the pistons ran into the valves. But why? I was traveling at less than 3,000 rpm. I replaced the belt, water pump and rollers three years ago and in that time it has seen redline at least once on every outing without so much as a hickup! Everything still looks almost new!
Any ideas as to what caused this?

And apparently this shows that the '97 engine is, indeed, an interference type.

Well I guess it's off to the wrecking yard on Monday for a new engine.

Regards,
M.Rad.

 

Why not pull the head and see what you got? I have had an engine that dropped a valve that wadded up in the head but I was able polish the top of the piston, go thru the head, head gasket, and it ran well for several years.

 

At this point, I think it would be less work to just replace it with a known good engine, than to do the cylinder head etc. Besides, I don't think I could trust the pistons any more, the possibility of an unseen crack or weakness is too great.
Of course I'd have to do some work on the other engine as well (timing belt, water pump, front and rear main seals, gaskets...) but it would be on a stand and easier to access everything.

Has anyone pulled a head while in the car, on one of these?
Regards,
M.Rad.

 

Hate to here of the loss. G.L.

 

Quick update-

I removed my original motor and pulled the passenger side head. Inside I found that all four pistons had "kiss"marks where the intake valves had contacted the pistons. I am still at a loss as to why the belt would have jumped timing, especially at the low revs I was turning.

I purchased a wrecking yard engine out of an LS, that they fired up while in the donor car. It started easily and seemed to run well- no noise, smoke, etc..
I brought it home and began stripping it down and cleaning / replacing as necessary. Oil pans and pick-up to swap, exhausts, engine mounts, new front and rear main seals, etc.

I also installed a new timing belt, and found that the tensioner roller was completely seized. I don't understand why the belt wasn't screaming when they ran it! I re-used the rollers from my original motor as they were solid and spun freely.

Anyway, it takes a while to clean off 19 years of accumulated grime and oil (valve cover and oil pan gaskets were leaking), but I'm in the re-assembly phase.

Just wish there was some way to run it on the stand to verify proper operation.

Regards,
M.Rad.

 

yeah its unfortunate when that happens, I had a 2uz drop a valve seat and I had to pull the head twice to fix it, first replacement head was bad also, I think going with a spare engine that you can see running is a good idea if you can swap it, good luck.

 

When I was a kid my Dad ran a VW shop. We used to start up the air cooled engines on the floor all the time. He had a bell-housing with a starter that had been cut off a transaxle just for it.

Always fun seeing fire shoot straight out of the heads.

 

Progress update: Engine is installed and running. I removed the hydraulic fan system and installed a fan pulley from the LS donor, along with an electric fan.
I 'm chasing a couple of codes (o2 heater, canister purge, cam sensor) but overall it still runs quite well.

Edit/ update- replaced O2 sensor, re-seated cam pos. sensor, re-routed canister purge lines and it runs great.

Regards,
M.R.