• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

Odd and maybe catastrophic engine noise.

1968 volvo

Well-known member
Joined
Apr 29, 2021
Location
Santa Rosa California
My pops and I went to the Davis meetup this weekend. It was an awesome trip and besides some overheating in heavy traffic, the 140 ran beautifully. It seemed we would have a successful trip until my dad (who was driving my 244) on the way home texted me and said that the car was making an odd noise after coming to a stoplight after a long stretch on the highway.


Now this noise is odd to me because it isn't steady like a rod knock or a valve clacking but it still sounds terrible. It's also not running very smooth at idle but that's not too unordinary. What do you guys think? I ran a compression test and its got even 150 psi across all the cylinders. The bottom end can be dead and you can still have good compression I guess. Is this a bad noise or a simple bolt is rattling?
 
Since you just put in the manual I'd make sure everything is still bolted up night and tight. Noise stay the same clutch in/out?
 
Run it up on jackstands and grab a stethoscope, I don't think the video is going to be enough to pinpoint much.

Sorry to hear the 240 is acting up but glad your 142 made it back without issue. Very cool car, awaiting the build thread
 
That's a tough one to hear what that could be. Try to track it with the stethoscope if you can't just find it by ear. a bolt rattling around in the bell housing can sound like it's from somewhere else.
 
That's a tough one to hear what that could be. Try to track it with the stethoscope if you can't just find it by ear. a bolt rattling around in the bell housing can sound like it's from somewhere else.
I’m person it’s pretty darn loud. It sounds like it’s coming from the block itself.
 
In your video it sounds like an exhaust leak to me. Perhaps, a chunk of gasket missing at one of the exhaust ports. Start it up with the engine cold and quickly feel around the manifold to head connections and manifold to down pipe connection for gases being expelled. A tiny leak can sound like a knock.
 
In your video it sounds like an exhaust leak to me. Perhaps, a chunk of gasket missing at one of the exhaust ports. Start it up with the engine cold and quickly feel around the manifold to head connections and manifold to down pipe connection for gases being expelled. A tiny leak can sound like a knock.
Good advice. I’ll check this too. I just recently replaced the exhaust gaskets and down pipe gasket as they failed at one point.
 
It kinda sounds like a problem I had awhile back that I didn't figure out until I pulled head. Could be completely off base, but it sounds similar so may worth mentioning.

It was the camgear bolt loosening and that tapping noise was the cam pin bouncing around the slot. It eventually got worse as it wollered out the slot.

 
I was typing out some advice and then I remembered one time I pulled a motor out to replace it because of a rod knock...and it was just loose torque converter bolts.

So yeah, my advice on weird noises is not to be trusted, hope you get it figured out and it's simple!
 
I was typing out some advice and then I remembered one time I pulled a motor out to replace it because of a rod knock...and it was just loose torque converter bolts.

So yeah, my advice on weird noises is not to be trusted, hope you get it figured out and it's simple!
Good point. OP just installed this transmission. Twice I have had cars where the torque converter bolts came loose and resulted in a knocking noise. The flywheel to crank bolts could be loose. As said above, get a stethoscope and narrow down where this noise is coming from. Eliminate all the accessories by disconnecting all the V belts and running the engine for a few seconds to see if the noise remains, or, suddenly disappears.
 
I disconnected the belts and stuff and it is not coming from the engine bay. It’s coming from under the car so somewhere in the new manual swap. Can a transmission itself make that noise or is it likely something else
 
If you run the car with the clutch in and shifter in gear (at a full stop) the input shaft won't turn. If the noise goes away an internal transmission issue is a good possibility, if not the issue is likely somewhere in front of the trans.

Not saying this is your issue, but as a practice I use loctite on flywheel and pressure plate bolts. A racket like that is about the least detrimental outcome if one of those has come loose.
 
Ya I really hope though that the issue isn’t a rattle inside the flywheel. I’m hoping to eliminate the actual gearbox too though. The passengers side motor mount is shot and I wonder if it isn’t something to do with that.
 
I have been digging and digging and diagnosing and listening and I can’t find anything making this noise. My listening tube seems pretty clear it’s coming from the bottom of the engine. If this noise is piston slap or some weird knock, how long do I have? My buddy in Oregon has a strong running na squirter block that could be mine if I make it there.
 
Here is something that is relatively easy to check: I once had a bolt fall out of the back of the block (it was one of those holding the main seal housing), and it made a terrible sound. It got stuck between the flywheel and the block, and generated so much friction that the engine didn't want to idle. If you pull off the alloy bracket that joins the lower bell housing to the block, you can look and see if anything is in there. In my case, I was able to drive the car some distance home, and when I found the bolt it was badly worn and showed signs of much heat from the friction.
 
I rebuilt a Karmann Ghia motor that had the flywheel nut come loose, and it made a similar sound, like a bottom end rattle/knock that didn't sound as rhythmic as a spun bearing. Bad news was that the loose flywheel destroyed the crankshaft. Considering it sounds like you said that part had been apart recently, I'd put my bet on that. An input shaft rattle from the transmission would stop if the clutch is engaged.
 
Back
Top