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Greetings all-
This is a follow up to my previous posting of a ticking that is becoming quite loud:
http://www.brickboard.com/RWD/index.htm?id=784976
Today I checked the clearance on the shims (B21F), and they were all in spec (.333-.381). The only thing that needed adjusting was that the bearing caps were really tight, so I torqued them to spec. So now I am still getting the noise which can be felt on the valve cover. The insides of the cam bearing caps looked fine, as well as the lobes on the shaft itself. Any ideas what to look for next? Rhys, do you have thoughts on this?
Thanks all-
Joe HC
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1977 244 160k (?), 1988 245 214k (soon to be dismissed), 1990 244 102k, 1978 Fiat 124 Spyder (restoring)
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posted by
someone claiming to be Rhys
on
Sun Apr 18 05:17 CST 2004 [ RELATED]
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Hi Joe;
I was out of town yesterday, so I couldn't check back.
Removing the caps one at a time is no problem, and a good idea as I mentioned.
The dampeners under the buckets will not create the noise you hear. Most of them are trashed in about 20k anyways, and do little.
If you are removing the cam soon, I can tell you a few tricks that avoid needing the special tool. I have removed and installed many over the years (its how I do valve adjustments in fact) and never broken one. They do, however, with abuse, snap.
Rhys
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Rhys-
Thanks for the info. This afternoon I am going to check the compression and see if all the buckets have the same resistance, then I'll report back under a new heading. I may take you up on that advice re: removal of the cam w/o a "special" tool.
Thanks-
Joe HC
--
1977 244 160k (?), 1988 245 214k (soon to be dismissed), 1990 244 102k, 1978 Fiat 124 Spyder (restoring)
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posted by
someone claiming to be Rhys
on
Sat Apr 17 05:30 CST 2004 [ RELATED]
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Hi Joe;
The spec you give at .333 - that's millimeters right? Something around .013 inch I think. That's OK.
From your description you lifted each cap off in turn to have a look. Good idea, and you found no wear on the bearings, lots of oil.
A broken valve spring would have caused a huge increase in lash. They have only one coil, and one broken end feeds into the other. Mostly the valve drops.
So the possiblities are:
A large piece of carbon has broken off and become pinched on the piston and the flat part of the head. This common on older domestic engines, but I have yet to see it on an FI Volvo. The cure is to feed some ATF into the intake while the engine is running at fast idle, smoke out the neighborhood, and burn away the carbon.
A piston has been damaged, and is cocking enough to hit the bore with the ring belt at the top, or one of the upper rings has broken and is feeding bits out into the combustion chamber. This I have seen, several times.
A rod bearing is going, and the clearance is allowing the piston to hit the head, or the knock is telegraphing to the head where you can feel it. I fixed a B30F that had that problem.
If it were mine Joe, given what I can get from the sound file, I would pull it apart and see. The head comes off quite easily, and that's enough to find the trouble more than likely.
Rhys
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Rhys-
Just to clarify, I actually didn't take the cam off, I just lifted the cap to check out where the cap and the shaft part meet. Nothing looked odd. Do you think it would be a good idea to do the ATF thing you mentioned? If so, where would you put it in at?
Thanks ALOT for your help-
Joe HC
--
1977 244 160k (?), 1988 245 214k (soon to be dismissed), 1990 244 102k, 1978 Fiat 124 Spyder (restoring)
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posted by
someone claiming to be Rhys
on
Sat Apr 17 05:34 CST 2004 [ RELATED]
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I just listened to the file again. The noise doesn't seem heavy enough for a rod bearing. Piston slap or knock maybe. Maybe a broken valve spring.
Pull the valve cover and push on all the buckets when they are in the up position. See if you can find one that is easier to push, or doesn't feel like the rest.
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I'll check the buckets in tomorrow and report back.
Thanks-
Joe HC
--
1977 244 160k (?), 1988 245 214k (soon to be dismissed), 1990 244 102k, 1978 Fiat 124 Spyder (restoring)
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Just another pair of ears, but I heard this in person and while feeling around the cam cover would have made a good wager Joe would find an obvious reason for it right underneath the cover at either #2 or #3. So I was pretty surprised to learn of the consistent good clearances and no evidence of oiling difficulties.
A local Volvoist who also owns a 77 just rebuilt the head and told me of brittle and cracked hushers. I've no firsthand experience with these or the bucket arrangement beyond glances in the JY, but is it possible one broken silencer is responsible for this? But the sound is the equivalent of my recollection of one bad hydraulic lifter on that type of motor, not a deep knocking or heavy sound, and if I recall right, it tends to fluctuate lower in volume with increased rpm and vary as it warms up-- which led me to guess something wasn't getting oiled well.
Pretty low of me to run off so quick and leave Joe to get his hands oily?
--
Art Benstein near Baltimore
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Art-
I am glad that I that you came by so I had another set of ears to hear the problem. I look forward to other's comments re: the broken silencer idea. BTW, the weather is nice here, and you could drive back out to help me solve this . . .
--Joe HC
--
1977 244 160k (?), 1988 245 214k (soon to be dismissed), 1990 244 102k, 1978 Fiat 124 Spyder (restoring)
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Rhys put that failed dampener wish to rest. Surely would be easy if true, but I guess it was far-fetched given I've heard two unopened 300K+ motors lots quieter.
On a mitsubishi I've had exhaust guides drop; I wonder if one ever walks up to get hit by the retainer. Never heard (read of) anyone complain of it either way on a Volvo.
--
Art Benstein near Baltimore
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posted by
someone claiming to be 81242DLB21FCA
on
Sat Apr 17 04:22 CST 2004 [ RELATED]
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Just finished listening to the wav file and reading your previous posts. Since the cam turns at twice crank speed, a rapid sound at idle is mostly likely valve train noise. If the tolerances are good, then I would guess any tapping noise is either the bucket hitting the valve stem or the valve hitting the seat. In your April 12 post you mention a loss of power. Therefore, I recommend a compression check before disassembling anything.
To me, releasing the cam using the bearing nuts is unsettling because the studs are not quit long enough to completely relax all the springs. Here is an improvised tool based on the one pictured in the green manual. Tighten the nuts untill the cross bolts contact the cam. Then remove the cam bearing caps. Finally, lossen the nuts untill all the springs are fully relaxed. The cam cover studs are more than long enough to do this.
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It is interesting that you mention using the bolts that hold down the bearing caps is not such a good idea to release the cam. This is the first time that I have done this, and I was relying on the info in the FAQS. In the Engine Mechanical---Cam Replacement section it says:
"Release each bolt approx. 2-3 turns and keep doing this till they are all loose. Make sure you record the order in which the bearing caps are removed: they are different and need to be replaced in the same order. The cam should gradually lift the cam caps as the nuts are released."
Is this incorrect, or am I interpreting this info incorrectly? Thanks for your help, I am jsut trying to understand the proper way to do this.
Thanks again-
Joe HC
--
1977 244 160k (?), 1988 245 214k (soon to be dismissed), 1990 244 102k, 1978 Fiat 124 Spyder (restoring)
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81242DLB21FCA-
Thanks for your perspective. I would like to try and make one of those nice tools that you posted. Do you have any guidelines for that?
Thanks again-
Joe HC
--
1977 244 160k (?), 1988 245 214k (soon to be dismissed), 1990 244 102k, 1978 Fiat 124 Spyder (restoring)
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That is a nifty looking tool you designed/constructed!! Next time I have to do head work I will certainly make myself one. I haven't broken a cam, but I also have been a bit leery of using the cap bolts to release the spring tension. This is another to add to the FAQs. Thanks,rcs
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What a great idea! I've read of a few broken cams on this site from uneven releasing of the cam bearings. Is this tool in the FAQs? If not, tell Ringlee about it.
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