timing belt slipped... what damage has been done?

[derelica]

To anyone out there. My 89 L300 had a timing belt slip on a logging road in Revelstoke. The vehicle stopped and I was able to dismantle the timing cover and crack the crank nut, retime the pulleys and reset the tensioners. It worked, and off we went. About 3km later she stopped working again. We rolled it back to a safe area not to far from my house. Next day I went back to check out what had happen. Looked as though there was some belt fragments that went through the timing belt on the second time and led to a more substantial slippage. I hoped for the best and re-timed everything again... this time, no start and hollow sound coming from engine. The engine turns but doesnt start.
Does anyone have some advice on what I should do next? I'm mechanically smart but think this may be getting over my head. is the damage going to be more than the valves? Any advice would be great. I have a good mechanic as a friend too!

[thedjjack]

Not sure why it slipped????

belt should never be able to slip.

Anyhow diesel motors have big compression way more then gas (this is why they do not have spark plugs the fuel gets compressed so much it explodes).

As a result there is no room for the open valves if the piston comes up. so if the timming is out enough that the piston comes up it will hit the valves. Damage? Depends on RPM, load, how off the valves are.

You can: bend valves, crack the head, distroy a piston, damage the cylinder, damage the crank, distroy the valve train, end up with metal through the motor.

If it was me...I would try to figure out why the belt slipped, very bad idea on a diesel motor. Next make sure the timing is good. Next pull the valve cover and see if you can see any valves that are stuck open or damage up top, check oil for metal.

If it does not run now...next pull the head and figure out the damage. (you could do a leak down test add psi to cylinder at TDC and lissen for leaks at head, crankcase, intake, exhaust (but you will still be pulling the head)).

Best of luck

[vixentd]

The first time your timing belt slipped the valves hit the piston, but as you say no serious damage was done. Unfortunately my guess would be that you actually bent a valve slightly. As the valve goes back and forth, it now will fatique as it bends back and forth and eventually will break off. This will cause catastrophic damage, often shredding the belt.

Hopefully this has not happened to yours. You need to remove the head and have a machine shop check the valves. You should not see any impressions on the top of the pistons.

[Golf Cart]

The thing with these engines is when the piston is at its furthest travel on the up stroke the top of the piston actually protrudes beyond the top of the block of each cylinder and up into the valve chamber, not by much, but enough to come in contact with the valve if the timing is wrong. If you were driving at 20kph, you can pretty much figure the valves have hit the pistons. Then to have it happen again you're almost certain to have bent a valve (or 4).

This happened to me when I was in neutral costing into a parking lot. Crank bolt sheared, causing the pulley to fall off, and stopping the engine cold. I ended up with 5 bent valves, 2 of which were seized tight. This has happened to me twice in total and both times it was more than a couple of valves. I took the head in and had the head rebuilt to the tune of a grand. And that was complete redo. Thats was on a Jetta head , so I'm guessing at least the same in price, cheaper if you do it yourself. That included a new head gasket and crank bolt and pulley, and I had to do the install.

Good luck

[jessef]

Belt slips, you put it back. Drives a bit and dies. Belt slips again, you put it back.

I sympathize but I don't understand why you pushed your luck the second time it slipped ?

Hopefully you'll be lucky with just the head and not a piston/crank/cylinder damage, otherwise a new engine is in your Delica's future.

This brings me to a point I've got to make as others will read this.

Since June (6 months - I've been counting) this will make 11 eleven blown 2.5L L300 engines. From what I've gathered around the shops, it's one of two things or a combination :

- lack of maintenance (timing - cooling systems)
- pushing the Delica too hard uphill / lugging instead of backing off the throttle

You guys reading this, please, please make absolute certain your timing belts/pulley/tensioners have been replaced at the 80/90,000km mark and done properly. Hearsay, or a previous owner who says it was done but can't prove it, is not the way to make sure it has been done. Unless you are 100% certain, please get it done.

And have the cooling system checked. Rad tested, waterpump/thermostat replaced (unless you know it's been done).

Hopefully, my post wakes up some people who are unaware of these things.

[lost2]

Just a few words to add on Jfarsang's comment:

I changed the timing & balance belts of my 1990 L300. It had 115 000km and belts had never been changed. At first, when looking from the top of the upper timing belt cover, the belt seemed AS IF IT WAS NEW (no cracks, no marks, i could even see the model number on top of it) but i choose to do it ... and discovered the balance belt WAS ON THE EDGE TO BREAK, covered with ton of cracks. What were the chances of this broken belt going into the timing belt run and making it slip, I do not know, but I feel a lot more confident using my van with new belts, tensioners, water pump and thermostat.

My sole regret: not having changed the two main radiator hoses and pressure checked the radiator.