What damage to '95 Volvo 960 2.9 liter w/broken timming belt?

JackC

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My son in law's timing belt idler pulley on this '95 Volvo 2.9, 6 cylinder engine broke and since it is an interference engine, it damaged internals to the point that installing a new belt and idler pulley did not solve the problem.

He tells me there is no compression in any of the 6 cylinders. He has not pulled the head yet.

Although the car is in very good condition, (except for this), he may not want to pull the head if we think it is a real disaster.

Knowing anything could be destroyed, like valves and pistons, I would like to know if any of you have been into this engine enough after a timing belt failure to guess what might be damaged.

Thanks, Jack
 

billr

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Have you pulled the plugs yet; are any beat-up down at the electrode?
 

JackC

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Bill:

I believe the plugs were fine when he pulled them to do the compression test. But I will not be able to contact with him for another day. I will let you know then.

I did discover from his wife, my daughter, that the exhaust manifold has been removed. That was the part he thought would be the most difficult to remove, and it was, requiring heat, etc.

Jack
 

billr

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I only asked about the plugs because sometimes, when something really bad happens in there, the debris will wipe out the end of a plug. That's a sure sign of doom...
 

nickb2

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This sounds like a major head rebuild, can't really tell if pistons were scored or punctured in the process until that head is pulled. Here is a picture of the head on valve side, note deep angle of valves in head. For sure many got real bent.

[attachment deleted by server]
 

JackC

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Nick: Great, but scary pictures. Thanks. Looks like intake valves don't get touched, unless they are hit by some flying exhaust valve pieces. The exhaust manifold is off as is fuel rail. He will be taking off intake manifold and then head perhaps this weekend.

If there is piston damage, he is not going to go any farther, as he has had some input that even the crank can be damaged. He is not willing to do a complete engine overhaul on this vehicle.

I will cross my fingers for him and also go down there and give him a hand. My 77 year old back won't do much, but I can take down some tools and hand him tools and be of moral support.

Thanks again, Jack
 

JackC

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Head off. Every one of the 24 valves hit a piston. Slight nick (more like a heavy scratch) in four places on all pistons. Most valves slightly cocked but just a few thousands off center. Looks like just a head refurb and 24 new valves will do it.

Upon reassembly, some techs suggest only torquing the head bolts by giving the final turn of only about 90 degrees instead of the specified of 130 degrees. Anybody have preference on that????
 

billr

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Does anyone know if those (OEM stock, I presume) pistons are forged or cast?
 

nickb2

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One question I feel stupid about asking is, is this engine turbo or non turbo, cuz usually there is a difference for pistons. A turbo will have lower compression and the company will usually install low comp pistons. Apparently porsche was part of the modular engine project for the 960. I would assume these would be aluminum cast with steel together maybe. I don't know. But I would surely get those pistons real clean first and look real close for any cracks, you never know, maybe even the skirt may have cracked around piston pin due to contact. Heres a picture of a piston with slight damage but you will see the damage not reparable. Rebuilding this engine will be a 60 40 deal. May work for a while and an unseen fracture may pronounce itself at some point. I know I would try it if rebuilding myself and I saw no visual damage other than a few scratches, but I can't SEE your damage, can you post a pic once cleaned the piston tops?

[attachment deleted by server]
 

JackC

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Thanks guys

I will have him check out those pistons as best we can when cleaned up. I don't think anything will show up in a picture. It will be a crap shoot, since it will cost about $500 for the valves, head refurb, gaskets, misc. even with all the free labor. Life is a gamble.

Anyone know about the 90 degree vs 130 degree head bolt torque question above??
 

nickb2

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I would stick with specs and use new bolts if recommended, maybe some ppl have experienced torque to yield problems by reusing the same bolts.
 

metricwrench

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JackC said:
Head off. Every one of the 24 valves hit a piston. Slight nick (more like a heavy scratch) in four places on all pistons. Most valves slightly cocked but just a few thousands off center. Looks like just a head refurb and 24 new valves will do it.

Upon reassembly, some techs suggest only torquing the head bolts by giving the final turn of only about 90 degrees instead of the specified of 130 degrees. Anybody have preference on that????
I would check the bolts for 158mm or less, clean threads, oily bolts thread & torque to specs (15-44- 130 deg)
wrench
 

billr

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I know that you are trying to avoid removing the pistons, but if you do, then have them dye-penetrant inspected. Only an opinion: I would never deliberately under-torque head fasteners, on any engine.
 

JackC

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My theory is that since the timing belt did not break, just the idler pulley bearing disintegrated the valve timing was just off enough for all valves to just barely touch the piston but not be wide open when things hit each other. We know it is still a crap shoot.

Thanks for the tips on the head bolts.

BTW, I am not getting notified via email anymore when a new post is inserted. Are you guys being notified?

Jack
 
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