Good Morning.

Going to work yesterday with my 144s, it sounded as if the engine was starting to ping under load. Coming home the ping turned into a metal on metal rapping noise, lotsa vibration, skips in the power, decreased power... a symphony of horrible noise. Any application of the gas brought on the BANG. Even downhill she ran horribly. I made it to the driveway, shut her off. When in the house for a much needed beer. Went out and started her up. Sounds bad, like loose metal wobbling about in the block. No smoke, no fluids, no external signs. Ran great yesterday.

I'm calling the Rx today... I know this one is beyond my ability. Any thoughts on what's in store?

Thanks.

I have had a connecting rod come loose in a B30 as well as running
something (a 5/16" nut) through a cylinder in a big-bore B20, as well
as failing numerous timing gears in B16, B18, B20 and B30 engines
(all use the same &%%$# gear). (The sound is a matter of degree but
you normally don't have anything to compare it to.)
From your description it could be any of the above. In any case you will
have to remove the timing cover sooner or later so you might as well
do it first. The gear may be in one piece still. You can rock the engine
back and forth and observe the point where the fiber joins the hub.
Easiest way to rock it is to put the car in 4th and roll it a bit each
way. If the gear looks good, then pull the plugs and shine a light in
there after looking at the plugs. Roll it to where the piston is at the top.
If you see a clean area corresponding to the flat surface of the head,
it is a rod problem. If you see a bunch of dents, you ran something through
it. (could be a piece of a valve)

Hope this is helpful,
GFD III
--
George Downs Bartlesville, Oklahoma

I haven't had time to check the timing gears, but I have a couple questions, if you don't mind:

If I find failed timing gears, what might be the result, or where do I begin to look, for the damage done by having driven with bad timing gears.

And why wouldn't failed timing gears just stop the car dead... like a broken timing chain or belt.

Craig

The timing gear can make a lot of noise and still work.
It will eventually let go completely and it won't run then.
The only thing that is damaged is normally the gear, although if it
breaks up into small pieces some may get into the crankcase.
This is usually not much of a problem because they are still too big
to get into the oil pump.
REAL Volvos do not have interference engines.
--
George Downs Bartlesville, Oklahoma

"...where do I begin to look, for the damage done by having driven with bad timing gears..."

Look no further than the timing gears. Nothing else breaks.

"...why wouldn't failed timing gears just stop the car dead... like a broken timing chain or belt...."

Sometimes it does. But what often happens is that the fiber gear breaks free from the steel hub and can "float" a bit, though it still rotates with the steel hub (and cam, thus turning the cam). So the gear sorta flops free, and is sorta captured by the hub -- and also constrained inside the aluminum cover. Thus it can really move around.

But more importantly, the cam is now free to slam a bit, and the force on the lobes from the valve springs "snaps" the cam from position to poition (the cam is no longer tightly tied to the crankshaft). This makes a racket until the fiber breaks completely, and then it stops dead, just as you said.

When you replace the gear set, be sure to check the small brass oil squirter bolt nozzel thingy. Make sure it's free and that the tiny pinhole is not plugged. Also be sure it's pointing at the gears.
--
Don Foster (near Cape Cod, MA)

That's really helpful... Thank you.

I had planned on doing some work next fall. Suddenly, NOW seems like a good time. I planned on pulling the head and having a shop upgrade the valves and seats - then putting it all back together with a new gasket set. I could use a new clutch . I'd really like an overdrive. Etc.

This is a 71 144S with 99, 246 miles. Well maintained, but I understand it may have been run rich... it did for me for a few months. My brother thinks the engine should be pulled for a little more work. That's fine, but I'm more interested in all-stock longevity than performance upgrades.

Any thoughts?

Craig

I will say upfront that I don't have any first hand experience with the 140 series... but after reading the BB for 4 years, and seeing this scenario come up several times, I will make an educated guess that your timing gear has failed. This is, from what I understand, a common problem area on high mileage B18/B20 motors. The fiber gear can apparently be replaced with a metal gear that should last much longer.

When the timing gear on my '72 failed, it sounded as you described.

When the timing gear on my '75 failed, it, too, sounded like this. That was around 150k miles.

When the timing gear failed again on my '75, at around 300k miles, it sounded as before.

I tossed in a set of B30 steel gears when I did the 2.2 liter high compression double valve spring K cam with headers fully balanced and other good stuff overhaul.

It stopped banging and started screaming after that. What fun.
--
Don Foster (near Cape Cod, MA)

Almost sounds like you lost a rod. From the vibration, it might still have the rod attached to the crank. Could you tell if you had lost oil pressure?

First port of call will be the timing gear. Grab hold of the crank pulley and turn the crank back and forth. If you feel free play before the cam starts to turn the gear is dead.


Regards



Pete

That was my crystal ball prediction as well. I've had the fiber gears come loose from the metal center and the resulting noise was horrifying - like a rod someone assembled without any bearing at all! Luckily for me my gear was an OLD OLD one and had a cast center with large splines the gear could still mesh with, so the cam timing wasn't affected and the engine still ran well even though the fiber part fell out when I took the timing cover off. Newer ones have smoother metal centers with smaller burrs to mesh with the fiber portion - so once they go they probably slip - causing odd things to happen with the valve/piston and ignition timing. These gears are one of the weak spots in the B18/20 design - they just can't seem to do quite the mileage the rest of the package can.

A mild word of warning (learned the hard way) - when you are replacing the gear be VERY VERY careful to not let the cam slide further back into the engine. There is a metal freeze plug inside the bellhousing behind the flywheel that can easily be popped out if the cam slides back. I was replacing a cam once on my 1800E. I was taking the old gear off the old cam by supporting the gear and tapping on the cam. When it popped loose it slid back and I heard a mettalic clatter back by the tranny. My cam swap suddenly became a cam swap and new clutch (might as well while its apart....).

That reminds me, shameless plug, I'll stick a camshaft gear installer on Ebay later today.

Regards


Pete

"when car engine make big bang, no run engine, just make worse"

Could be a lot of things, hard to say over the radio. As bad as rod maybe a rod end bolt....I suspect one bucket isn't firing. Remove all spark plugs, have lovely assistant turn engine over, what do you feel with thumb, see with eye?

I guess you had planned on a rebuild anyway. IF my car makes such noises the typical response is to not carry on unless you don't care....or someone is chasing you.....
--
http://www.fidalgo.net/~brook4/oilslubesfilters.html