My 1987 Volvo 740GLE non-turbo was not starting. I replaced the engine wiring harness, coil, and power stage module. The car still did not run. I asked a mechanic to take a look at it and, he immediately found the problem. The timing belt was broken and, upon later investigation, the mechanic replaced the timing belt with a new one and, the car attempted to run but did not. The car had broken the new timing belt and several of the teeth on the lower wheel were missing. The mechanic does not think there is a problem with the crankshaft or pistons. He believes the problem may be at the overhead cam area. Does anyone have any suggestions?

sounds like first you need a new mechanic
your old one might just be your problem
i always had rotate a few times to make sure every thing feels right then start it up the first time back with the front cover off watching to make sure everything looks right as it is turned over

I spent the last few days taking care of other business. I finally got in touch with my mechanic. He told me that upon further inspection, one of the Crankshaft bearings had seized, thereby creating enough drag to break the timing belt at the crankshaft. He said it was a "strange" occurance that he had never seen before in any of the Volvos he worked on. Does this make sense? He said the repair is simple enough and, shouldn't be more than a couple of hundred dollars including parts and labor.

Now the mechanic tells me that he thinks the oil pump might have seized and be the culprit. What do you think? I have not found anything on the 700/900 FAQ to help. Any suggestions where I might find the answer?

Tell us what the mechanic did or saw that made him change his mind from suspecting the top end (most likely)?

Without knowing what's going on between posts, it's impossible to make relevant comments.

Did you do a search here on "Siezed Cam" as I suggested yesterday?
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

The mechanic said that the cam appeared to be in good shape. He said he had replaced the belt and started the engine based on my telling him I had not had any other problems with the car. He said that the car started momentarily, then quit. He then inspected the belt again and it was broken. He told me that the engine appears to be in good condition and he does not suspect problems with the crankshaft or piston assemblies. He did say that the oil pump on these cars can seize and jam the lower part of the belt. Does this seem right to you? I did not have a chance to search for seized cam shafts but, I will do so momentarily.

It is the camshaft bearings that seize. The only way to be certain is to remove the bearing caps and look. It seems doubtful that the mechanic looked at all the bearing surfaces. "Camshaft looks good" is therefore meaningless.

I, too, go with the seized camshaft diagnosis.

Not a bad job, just a lot of take-it-off and then put-it-together. Have you looked for a sharper or more knowledgeable mechanic?

When a timing belt "breaks" it very seldom actually breaks. It fails when a number of teeth are sheared off the belt at the section where the belt wraps the crankshaft drive gear.

Good Luck,

Bob

:>)

He did say that the oil pump on these cars can seize and jam the lower part of the belt. Does this seem right to you?

No, It does not seem right. For three reasons:

1) In 2+ years here, and 15+ years of 240s, I've not heard of an oil pump siezing. Siezed camshafts, while not frequent or common, are a failure which is known to result in snapped belts.

2) The Oil pump is driven by the Intermediate Shaft, where the timing belt has the least amount of contact, and thus the least likely to break the belt if it did sieze. Maybe strip some cogs, but see #1.

3) The oil pump (and intermediate shaft) are associated with the middle (i.e. "intermediate") part of the belt, not the "lower part of the belt", where the turning force is exerted by the crankshaft.

Maybe we've lost something in translation here, but my money is still on the camshaft.

EDIT: Maybe your mechanic can show you which shaft is siezed, if the upper timing belt cover is off. The camshaft is normally hard to turn, due to valve spring resistance, and requires a wrench on the sprocket bolt. But the Intermediate shaft should turn easily by hand. If it's jammed for any reason, it should be obvious.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

What do you mean by "several teeth on the lower wheel were missing"? The mechanic should be able to turn the camm shaft, counterbalance shaft and crank manually to determin if there is any bearing problems. If the tensioner was not installed properly the new belt may have jumped off one of the sprockets. It's always a good idea to turn the engine over a few times by hand after a new belt is installed to make sure everything is aligned properly and rotating smoothly.

"The car had broken the new timing belt and several of the teeth on the lower wheel were missing."

I think your mechanic meant that several cogs were stripped from the belt at the lower whhel (crank sprocket). As Chris says, this points to a siezed camshaft.

Use the Search Feature up above to look for siezed cam. I saw lots of hits, and hopefully some tips there will help you.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

It sounds like the cam bearings siezed. Generally this happens due to insufficient oil circulation to the bearings caused by sludge building-up in the oil passage up through the head. I had an 82 240 that did the same thing. It was my fault for not changing the oil on schedule.

You can often times get away with pulling the cam out and cleaning up the bearing surfaces on both the cam and the caps and saddles, and putting it back together. The oil travels up through one of the head bolt holes - I believe it's the second one back, but I don't remenber which side. Anyway, you need to remove the bolt and clean the sludge out. While the timing belt is off, you should be able to spin the intermediate shaft in its proper direction with a drill motor and pump oil up through the passage.

Hopefully someone can ring in with the correct head bolt to remove.

When mine did this, a local mechanic got it going the way I describe. But when he was done, the valve train was kind of noisy. If I did it again, I would be tempted to plastic-guage the bearings after they're cleaned up, and if they are too sloppy I'd maybe run the cap mating surfaces over some sand paper and try to get the bearing clearance back closer to tolerance. But that may in turn tighten the valve lash a little to close. You'll likely have to recheck the valve lash and re-shim if necessary.

Oh, BTW, don't forget to change the oil. Good luck.
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Chris - 1990 740, 1973 1800ES (Non-running), 1993 Dodge Dakota (Still has a little paint left on it)