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timing belt/ no start ?

1

1rockhead

New member
Joined
Feb 25, 2018
My 1990 240 is not starting again. It cranks over but the timing belt does not move. It is not broken and the drivebelts still move. Is this likely a timing pulley problem?
 
What would cause that on a new belt? I has this happen before and when I pulled the belt it was missing a couple teeth. I checked the camshaft last time and it had no signs of seizing.
 
Under tension can cause it to slip and strip teeth. I knock the tensioner tight with a flathead screwdriver and a hammer. The spring isn't good enough.
 
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Its easy to make it too tight. You dont wanna be able to "play the harp" tight, but not so loose it will slip either. Another trick with timing belts is to use those black metal paper clips (the ones with a pair of swing arms) to hold the belt onto the gears while doing the job. Then you always turn the gears with a solid breaker bar (non ratcheting) and tap em so the slack is on the TENSIONER SIDE of the belt, THEN you pull the pin and knock the belt tight.

I've done plenty of belts on different engines and they can be very tough to keep the belt on the gears and then have enough slack in the correct spot to even get it over the last pulley. (Like V6 Toyota engines.) Scoobie engines I use the same method.
 
there are later round tooth and earlier square tooth timing systems on redblocks, sometimes people screw up and mismatch them. engine swaps and frankenstain setups can mistakenly bring them together. worth a check that all three gears and the belt match.
 
I did notice the belt seemed very tight. I put a new tensioner on when I changed the belt 100 miles ago. I will also confirm all the teeth are the same. I had noticed that intermittently it would turn over with no compression but then it would catch and have compression. is it possible for the crank to turn the drive belts but the timing pulley attached to the crank not spin?
 
It’s important to note that you need to fully seat the harmonic balancer against the key way before tightening the crank bolt, otherwise that will attribute to breaking the key way. BTDT
 
Thanks... Now I at least have a direction to head in. If it is the crank gear is the europarts version good enough? It is $20 versus $60 for the IPD version.
 
Have you even taken the upper cover off yet, and looked down the hole to see if the crank sprocket is actually turning?

The sprocket locks to the crank. The balancer locks to the sprocket. All clamped together by the huge center bolt.

Logically, if the bolt is loose enough to strip the sprocket's keyway protrusion (letting the sprocket not turn with the crank), that would also tend to allow the balancer to freewheel on the bolt, unless you managed to strip both "nibs", and the balancer is just spinning due to friction from the crank.

I tend towards the "2 minutes with a flashlight" option before throwing money at parts I may not need.

<img src="https://d354nuoz4t18d4.cloudfront.net/images/996a7fa078cc36c46d02f9af3bef918b/152dbf0abbd28b3d7046e90539684136.jpg" width=400></a><img src="https://www.rockauto.com/info/4/102089_1__ra_p.jpg" width=400></a>
 
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