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Hi all,
My amazon still has it's 1969 B20B in it, waiting for the B20E currently being rebuilt. As progress is slower than expected on the latter, looks like the "B" is going to serve a little longer than expected.
What worries me is that i have a few longer trips scheduled for this spring and since about 10kmiles, the engine has been producing a noise that sounds like a shot piston axle to me (same as a misadjusted valve but they're all as smoothly set as they can be...)
In the event it actually is a piston axle, is it sensible to think that the engine can last another 4'000 miles or so or should I just quit my job to have the "E" in ASAP?
Youre experiences in piston axle fault diagnosis and life expectancy?
Thanks in advance, Séb
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Gringos call the "piston axle" a wrist pin. Brits call it a gudgeon pin.
I think your problem is a timing gear also. It is a near-universal fault
with the B16/B18/B20/B30 engines till you put in a metal gear.
--
George Downs Bartlesville, Heart of the USA!
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Hi George,
Thanks for this useful language precicion: piston axle wass indeed a direct translation from French!!
Regarding the timing gears, why the hell did volvo come up with the fiber one if steel ones are so desirable? Weight (haha ;)), cost, some hidden advantage I can't make out?
Cheers, Séb
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I think maybe it was sort of a safety precaution, a weak link, so for example
if the distributor seizes, or some such the gear will crumble.
Also they are pretty quiet. Maybe cheaper too, although I think the teeth
are cut rather than molded, so precision machinery was indeed necessary.
The B16 used the same gear. I don't know about earlier models but the
B4 and B14 are a lot like the B16 so maybe they did too.
--
George Downs Bartlesville, Heart of the USA!
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posted by
someone claiming to be cdu
on
Mon Apr 11 08:03 CST 2005 [ RELATED]
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A friend with a 122 recently complained that he was driving
on the freeway and the motor sounded funny, then made a loud
bang and the car stopped running. I came over, mucked with it
a bit, then took the distributor cover off and saw that the
rotor was not turning when the motor was cranked.
I then took the valve cover off and was greeted with only
7 pushrods instead of the more common 8. I have no idea
where the last one is hiding though I wouldn't be surprised
if it was playing with the camshaft right now and that is
why the cam and dizzy aren't turning (stripped timing gear).
If the car weren't a rust heap it might be interesting to see
how hard it is to get running. As is, it will be an organ
donor...
Maybe the fiber gear here saved the motor from totally
grenading.
chris
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If a gear gave up the ghost then you'd still have 8 pushrods in place. The cam must have broken somehow.
--
I'm JohnMc, and I approved this message.
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posted by
someone claiming to be cdu
on
Mon Apr 11 17:51 CST 2005 [ RELATED]
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I was thinking more that he somehow bent then broke a pushrod
and that the pieces fell down the pushrod hole and those pieces
jammed against the lifter / cam and froze that into place, thus
breaking the timing gear. There were no holes or other places
for the pushrod to hide, though I will admit that I didn't look
down to where the lifter lives to ask it what happened.
"The car was making a noise. Then it made bang and stopped
running."
Indeed. I can see that now.
chris
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In my year of Volvoing I have had 4 instances of bad timing gears (or variations thereof) which resulted in keep knocking noises that sound EXACTLY like rod knocks, only occuring at different times and under different conditions. I've actually had a rod knock only once (after about a year of 7K rpm zings on a shade-tree rebuilt bottom end). It sounded about the same.
Cam knocks (from bad gears or worn thrust plates allowing the cam to knock back and forth) - knocks at idle, and fades as the rpms rise.
Rod knocks - can occur at any speed, more sensitive to the load on the engine, quets down more at idle. When I had the spun rod bearing it was perfectly quiet at idle, unless I pulled the #2 plug wire - at which point it would start gently knocking again.
--
I'm JohnMc, and I approved this message.
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Hi John,
Thanks for this quick input.
Guess what: I didn't even think of the cam! And it sounds like you got the right diagnosis, because the noise fades and eventually disappears totally as the RPM go up.
The mileage of the engine is unknown, but it still pushes hard although the rings must have seen better days (oil comes out from the oil filling cap quite a lot, no PVC installed though).
This being said, have you experienced long service period with worn out timing gears or is this a "fix it or it'll die soon" situation?
Also, do you know where to source new thrust plates in europe?
Thanks for your help,
Séb
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Depends on what is causing the noise. Loose thrust washers will rattle and knock for a VERY long time, not much to worry about. But loose gears (the nut backed off and it is coming off the cam) or separated gears (the center metal section comes loose from the fiber outer section) are not going to last long at all. You could pull off the timing cover and take a peek, or just keep driving it. No real damage takes place when a timing gear lets go, and it isn't much more work to replace a gear than it is to take a quick peek at one (although you have conrtol of when you take a peek!).
Well - I take that back - when I had a gear come loose once it allowed the cam to slide backwards until the fornt bearing was rubbing on the #1 lifter. Which ruined the lifter and the lobe, neccesitating a pull of the head to replace lifters and cam along with the gear.
--
I'm JohnMc, and I approved this message.
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About how many miles does this engine have on it since the last rebuild? If it's been properly maintained with regular oil changes, etc. you should still have a lot of miles left in it.
To track down the source of your knock, try a mechanic's stethoscope. I thnk I bought my last one for $4 at Harbor Freight. If you can't find a cheao one, use a short length of garden hose, or even a stick that you can rest against your mastoid bone behind your ear.
It should allow you to localize the noise to a specific area, if not right to a defective part.
With 5 main bearings, I'd agree with JohnMc; it is most likely a cam knock - although with worn rocker faces, you can't adjust those properly using a blade-type feeler gauge.
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Thanks for the idea of the stethoscope, barongrey. I fear hardware is not as cheap here in Switzerland/Europe than in the states, but I definitely can source some garden hose in the very near future! I knew about the method, but only did it with a screwdriver, thus limiting the trange of nmy hearings!
Your help is highly appriciated, cheers, Séb
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You're living in Europe and don't know where to find Volvo parts!!! I wish I had those problems. Buy a copy of the German classic car magazine MARKT. Look in the classified advertising section under "Volvo". There are at least 6 very good and knowledgeble sources, almost all with websites. I agree about the timing gear analysis. Been there. It seems to be true that the loudest and most scariest noises turn out to be the less complicated fixes. It's the small and hard to hear noises that will bite you in the bumper.
I have in my parts bin an ALUMINUM (Aluminium, for you Brits)timing gear. Appears to be used, but unmarked. Anyone have any experience with one. Should I try it out, or leave it in the bin? Also, there are some Japanese timing gears in circulation, are they a good alternative to OEM?
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If it's made by Cloyes, I'd be happy to use it -- see pic below for what that looks like. If it's some other brand, I'd be scared of it.
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