BIG problem

G

G.M.

Well-known member
Went on a test ride this morning. Went 30 miles on straight highway
everything was perfect. Had lunch checked under the hood including
oil and water, all was good. Came back 28 miles, about 2 miles from
shop and for about 1 1/2 miles at 45 MPH started sounding like fuel
ping, we filled the tank before starting and thought the new gas was
pinging. This was not loud. Then all of a sudden a big bang and the
engine stopped.Coasted into a parking area. The engine was hot. We
stopped about 5 miles before this and everything was OK. WE were
watching the oil pressure all the time and it was 45 lbs steady. Called
AAA and they took it to my main shop. I don't need a lot of guessing
as to what the problem is but sounds like a rod or piston. Will tear
the engine out later next week and report the problem. Not to Happy.
G.M.
 
1) "Engine was hot"
2) "Sounded like a fuel ping"
3) "Large bang"

I have had overheating problems that would result in fuel pre-ignition and if the overheating went on long enough, there could certainly be a big bang. You didn't mention anything about what you saw on the water temp gauge. Pulling a head may certainly answer a lot of questions. Sorry about this new development...it sucks.
 
Capt Kirk said:
1) "Engine was hot"
2) "Sounded like a fuel ping"
3) "Large bang"

I have had overheating problems that would result in fuel pre-ignition and if the overheating went on long enough, there could certainly be a big bang. You didn't mention anything about what you saw on the water temp gauge. Pulling a head may certainly answer a lot of questions. Sorry about this new development...it sucks.
Click to expand...

I'm not going to waste time pulling a head, which one?? And that won't
show the bottom end where I'm sure the noise came from. Heat gauge
was a new reproduced replacement that didn't work good when installed
and stopped working completely reading zero. Had the laser thermometer
we used and stopped frequently to check temps which were about 160.
I don't even want to crank it by hand until I pull the engine. I could drop
the pan but that's a pain. I have several other engines that I can drop in
if I need one. I just had the radiator out and that's the worst of the
engine removal so it won't take long. We had this same ping about a
month ago before I did the radiator and adjusted distributor and it
stopped. G.M.
 
jimTN said:
Could have been a fiber timing gear letting go slowly.
Click to expand...

It started up after the big bang although there was a big backfire.
I only ran it about 2 seconds. I may pull the front gear cover after
the radiator is out. G.M.
 
I would have Skip check the distributor first. I had a condenser go bad, caused a big loud backfire and set both K&N air cleaners on fire. Hope it is something simple but this stuff is up to 85 years old.
 
GM, I'm keeping my fingers crossed for you. Only you know what the "bang" sound sounded like and you've been around long enough to know if it's a catastrophic failure. I had an engine failure in my Maule which, according to the aircraft mechanic, said the wrist pin broke which broke the cam in several places. There was no doubt in my mind that what I was sitting behind was a wind powered metal pulverizer. Pilot seat upholstery needed a little repair on that one too!
 
G.M. said:
I'm not going to waste time pulling a head, which one?? And that won't show the bottom end where I'm sure the noise came from.
I don't even want to crank it by hand until I pull the engine. G.M.
Click to expand...

I would take the plugs out and pull it through by hand. If it has a busted piston or a messed up rod bearing, you should be able to feel or hear something. If there is damage, it's already done. You can't hurt it any more than it already is turning it by hand. If it turns through two revolutions without any indication of a problem, I would try to do a leak down type compression test.

I like to at least have an idea what might be wrong before I tear into things. I've saved myself a lot of work this way in the past. If a rod let go it will usually damage the block and it will make a lot of noise flopping around in there. A bad bearing should have been knocking as it was shutting down.
 
Last edited:
rotorwrench said:
I would take the plugs out and pull it through by hand. If it has a busted piston or a messed up rod bearing, you should be able to feel or hear something. If there is damage, it's already done. You can't hurt it any more than it already is turning it by hand. If it turns through two revolutions without any indication of a problem, I would try to do a leak down type compression test.

I like to at least have an idea what might be wrong before I tear into things. I've saved myself a lot of work this way in the past. If a rod let go it will usually damage the block and it will make a lot of noise flopping around in there. A bad bearing should have been knocking as it was shutting down.
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I agree. Kinda what I was hinting around about. BUT...GM knows the sound he heard and he's no stranger to this stuff. If a rod or piston is gone, he knows that sound. I recommended pulling the heads which is easy on a flathead. If a piston is gone...question answered. If a rod is gone, that too can be answered. Pulling my engine would be a major ordeal and I would want to investigate before I did that. Maybe GM has the means to get an engine out lickity-split and it would be easier for him doing it this way. Not having heard the sound, there's probably 10 things I'd do before pulling the engine but that's just me and my work environment.
 
Your probably at it today, goodluck, be safe & hope it's not as serious as you think. I agree with your rational on engine removal. If you've got the stuff in front of the engine removed already the engine removal is pretty easy. As your posts indicate everything you need to check is much easier to get to after that.
 
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