Hi Everybody,

1987 740 turbo, B230FT engine.

I've changed a few timing belts in my time, but this is a first.

After changing all front oil seals, I put a new tensioner (INA) on and slipped on and aligned new timing belt to the pulley wheels. Once I released the pin to let the tensioner take up slack, I rotated the crankshaft 1 whole revolution (CW) and the belt was starting to slip off the tensioner roller. If I go 2 revolutions of the crankshaft, the timing belt is barely hanging on the roller. Yes, the hanging pin of the tensioner is pushed into the background hole in the front of the engine.

I had torqued overhead camshaft bolt to 37 ft-lbs but had not yet torqued intermediate camshaft to that spec. Is not torquing intermediate camshaft bolt to that spec part of the problem because it's not properly aligned with the overhead camshaft?

Any ideas? Thanks.

 

Make sure the harmonic balancer/crank pulley are lined up properly, they're keyed but I've seen the pin get smashed and whatnot. Also make sure those stay plates are in place on your crank pulley for the timing belt.

My timing belt slipped off when my harmonic balancer flew off while driving. It was a mess.

 

Did you remember to put back the alignment keepers for the timing belt on the main crank gear? I forgot to put that back one time, and the same thing was happening.
[align=left] [/align]

 

Like stated already make sure the washers/spacers on the crank are set correctly.

 

Thanks, guys. Yes, I have the back crankshaft shim (which doesn't lock to crankshaft); pulley boss (or gear), which is keyed to the crankshaft; front crankshaft shim, which is keyed to the pulley boss; and the crankshaft gear/harmonic balancer, which is keyed to the pulley boss.

I suppose I had better doublecheck that there is no burr or something like that on the crankshaft that is hanging up the front shim. Still, the alignment of the intermediate camshaft over the crankshaft looks dead on.

But, I will check.

 

Oh, I forgot. Playing around with all this, I still haven't torqued down the crankshaft bolt yet. Could this be the problem?

 

It is possible it is causing it.
Also may sound like a stupid question but did you possibly swap the intermediate shaft pulley and the cam one?

 

Tech, nope. They're put on correctly. I labeled overhead with an "O" and intermediate with an "i," respectively, when I took them off.I also did remember to put the washer behind the overhead cam gear. There was no washer for the intermediate.

 

OK are you sure the washer was behind the cam gear?
Some had them but alot didn't have the washers. But the washer would fit unless it is supossed to be there it would have to have the hole to slide over the pin to fit. If you look from the side of the car does any of the pulleys look out of line?

 

The washer has a slot to fit over the cam key. Yes, it was behind the gear because I took photos almost every step of the way. What I did discover, looking back at some of the photos, was that the cylindrical hole (on left) of the tensioner guide rod was out a bit rather than being pushed all the way in over the protruding guide post on front of engine. Maybe I just have to adjust this so as to tilt the roller.

 

Try that and see if it helps.

 

Tech, update.

1) pulled crankshaft pulley, shims, and pulley boss and made sure everything was pushed up tight on crankshaft.
2) torqued crankshaft bolt to 100 ft-lbs. Better, but belt still slips.
3) Seems that overhead camshaft pulley could be pushed forward 1/8 - 1/4", since the belt slips off about that much after several revolutions of the crankshaft. Strange. There was no problem with the old belt and tensioner roller for the current overhead camshaft. The original keyed washer is in back of the overhead camshaft pulley-its original position.
4) May put in old tensioner roller tomorrow and see if that helps.

This is really strange! Am I missing something?

Thanks.

 

Maybe try removing the washer behind the cam gear and see if that fixes it.

 

I would have thought I needed another washer in there from the angles. But, you might be right. Will try that tomorrow.

Thanks!

 

Let us know how it goes.
Like I said earlier alot of the cars don't even have the washer from the factory.

 

Tech,

Removed the 2-mm washer; didn't help. The belt still slips off.

I may have to put another washer in there, or perhaps the cam gears are old and the teeth are rounded.

Also, I'm using a Conti-tech belt. I heard they have a good reputation.

What do you think? Should I get new cam gears?

 

Heck of a time for me to remember and ask this.
But also make sure the belt is the proper one. The Later model cars have round teeth belts. The older cars have the square teeth belt.
Make sure you have the correct belt.

 

Tech,

Finally figured it out. The new INA tensioner roller has a flat back hanging plate (against front of engine). The old INA tensioner roller has a small angle bend in that plate, enough to ensure that belt does not slip off.

 

OK glad that you figured it out.

 

Oops, the saga continues. A professional mechanic said the back of the hanging plate on the tensioner is supposed to be flat. "Something is out of alignment," he said.

He will be coming over to look at it. I'll keep you all informed.