350 ticking after electrical short
Thread Starter
Registered User
Joined: Mar 2014
Posts: 23
From: Vienna, AT
350 ticking after electrical short
Hi guys,
The Olds 350 in my 1979 Custom Cruiser was running perfectly fine. The starter was acting up though. So I put together a supposedly good one - out of three I had sitting around. A professional mechanic installed it, cranked the engine several times, and drove the car for 20 minutes. Suddenly it caught fire from wires burning up. He blamed my starter as the reason. I cannot imagine he made a mistake mounting it - after all what can be done wrong?? Maybe it was a coincidence. Anyhow, in the process the new starter melted down, as did the ground wire connecting it to the frame. The frame became so hot that the brake fluid boiled up in the lines running alongside it and the main brake cylinder was shot as well. So things REALLY got hot. Luckily, the vehicle was saved from total loss by the mechanic pulling the negative battery cable...
The car is back on the road a while now but there has been a noise ever since that I classify as valve ticking. It gets worse with the engine oil warming up and both in idle and under load. Cylinders 5 and 7 (the ones next to the starter) show only 5,5-6 compression reading (taken on the cold engine, other cylinders around 8,5). Overall engine performance is a bit sluggish, idle is uneven and rough.
Oil has been flushed and changed, there is no smoke from the exhaust, oil and coolant seem "clean". As far as there is valve adjustment on those engines, it seems fine. I torqued everything down to specs. Pushrods look fine. Ignition timing is set 20° btdc, as suggested on the emissions label.
So here`s my thesis: I assume the (intake) valve lifters on cylinder 5 and 7 got hot and damaged somehow, not opening the valves properly anymore, thus letting in only a limited amount of air/fuel mixture resulting in low compression - and ticking noises. This gets worse as oil pressure declines (as engine warms up).
However, before I pull the intake manifold I would greatly appreciate any suggestions if this theory is plausible - and if there are other things that can / should be ruled out before!?
Many thanks in advance!
The Olds 350 in my 1979 Custom Cruiser was running perfectly fine. The starter was acting up though. So I put together a supposedly good one - out of three I had sitting around. A professional mechanic installed it, cranked the engine several times, and drove the car for 20 minutes. Suddenly it caught fire from wires burning up. He blamed my starter as the reason. I cannot imagine he made a mistake mounting it - after all what can be done wrong?? Maybe it was a coincidence. Anyhow, in the process the new starter melted down, as did the ground wire connecting it to the frame. The frame became so hot that the brake fluid boiled up in the lines running alongside it and the main brake cylinder was shot as well. So things REALLY got hot. Luckily, the vehicle was saved from total loss by the mechanic pulling the negative battery cable...
The car is back on the road a while now but there has been a noise ever since that I classify as valve ticking. It gets worse with the engine oil warming up and both in idle and under load. Cylinders 5 and 7 (the ones next to the starter) show only 5,5-6 compression reading (taken on the cold engine, other cylinders around 8,5). Overall engine performance is a bit sluggish, idle is uneven and rough.
Oil has been flushed and changed, there is no smoke from the exhaust, oil and coolant seem "clean". As far as there is valve adjustment on those engines, it seems fine. I torqued everything down to specs. Pushrods look fine. Ignition timing is set 20° btdc, as suggested on the emissions label.
So here`s my thesis: I assume the (intake) valve lifters on cylinder 5 and 7 got hot and damaged somehow, not opening the valves properly anymore, thus letting in only a limited amount of air/fuel mixture resulting in low compression - and ticking noises. This gets worse as oil pressure declines (as engine warms up).
However, before I pull the intake manifold I would greatly appreciate any suggestions if this theory is plausible - and if there are other things that can / should be ruled out before!?
Many thanks in advance!
Running On Empty
Joined: Jul 2018
Posts: 26,201
From: Earth
Certainly happy you had no fire. I'm curious regarding a couple statements you made:
(1) You stated the noise gets worse w/ the engine oil warming up at both idle and under load.
Questions: Does the speed (rate) of the noise increase as engine RPM increases and does the speed (rate) of the noise decrease as engine RPM decreases?
When you state the noise gets worse, do you mean to say the noise gets louder w/ the engine oil warming up at both idle and under load?
If you have not done so already:
(1) Remove every spark plug and evaluate each spark plug for damage (I believe I'd replace all spark plugs w/ new spark plugs);
(2) Evaluate HEI distributor cap, ignition module for cracks, arcing, etc.;
(3) Evaluate spark plug wires for damage/resistance;
(4) Any other engine electrical device for damage (e.g. alternator, etc.).
You can take a wooden broom handle (or engine stethoscope) and hold it against areas of the engine (valve covers, block, manifold, alternator, etc.) and see if you can better isolate the location of the noise.
It's certainly possible you have valve &/or piston ring damage, but I'd check all engine electrical components first.
Regarding compression readings. I don't know about 5,5-6 and 8,5 compression readings. I generally measure compression readings in psi, so I'm not familiar with those readings and can't say if the difference is significant. What units of measure do those readings refer to?
I believe the 350 cid should deliver somewhere in the range of 130 psi to 160 psi. You could do a compression test both dry and wet. Measure/Record each cylinder compression dry. Insert roughly a tablespoon of engine oil into the cylinder you measured dry. If the compression increases it might suggest a cracked piston ring(s).
(1) You stated the noise gets worse w/ the engine oil warming up at both idle and under load.
Questions: Does the speed (rate) of the noise increase as engine RPM increases and does the speed (rate) of the noise decrease as engine RPM decreases?
When you state the noise gets worse, do you mean to say the noise gets louder w/ the engine oil warming up at both idle and under load?
If you have not done so already:
(1) Remove every spark plug and evaluate each spark plug for damage (I believe I'd replace all spark plugs w/ new spark plugs);
(2) Evaluate HEI distributor cap, ignition module for cracks, arcing, etc.;
(3) Evaluate spark plug wires for damage/resistance;
(4) Any other engine electrical device for damage (e.g. alternator, etc.).
You can take a wooden broom handle (or engine stethoscope) and hold it against areas of the engine (valve covers, block, manifold, alternator, etc.) and see if you can better isolate the location of the noise.
It's certainly possible you have valve &/or piston ring damage, but I'd check all engine electrical components first.
Regarding compression readings. I don't know about 5,5-6 and 8,5 compression readings. I generally measure compression readings in psi, so I'm not familiar with those readings and can't say if the difference is significant. What units of measure do those readings refer to?
I believe the 350 cid should deliver somewhere in the range of 130 psi to 160 psi. You could do a compression test both dry and wet. Measure/Record each cylinder compression dry. Insert roughly a tablespoon of engine oil into the cylinder you measured dry. If the compression increases it might suggest a cracked piston ring(s).
Barely Registered
Joined: Feb 2014
Posts: 2,648
From: Gillespie County, Republic of Texas
Running On Empty
Joined: Jul 2018
Posts: 26,201
From: Earth
Gary - I initially suspected it might be the bar equivalent to psi (14.7) but when I arrived at the numbers (as you posted) they didn't appear to fall w/in the range of compression for a 350 cid, unless I'm incorrect w/ regards to the cylinder compression ratings for a 350 cid 1979 Custom Cruiser. Perhaps I'm incorrect. I realize there is more to determining the final engine compression ratio of any engine, but w/ regards to the stock 350 cid, I always thought somewhere in the range of 130psi to 160psi was an acceptable range. Readings of 5,5-6 (81 psi-88psi) appear well below average, IMO. Maybe I'm having a Monday or perhaps that is the true readings and again, that's far below average, IMO. Additionally, no cylinder should be less than 80% of the highest cylinder and no cylinder should be less than 100psi. It would appear cylinders 5 & 7 are far below 100 and well below 80% of the highest cylinder.
CH3NO2 LEARN IT BURN IT
Joined: Jul 2010
Posts: 5,643
From: Land of Taxes
Good basic trouble shooting rolled out here.
Always start simple. Intake removal would be at least 10-15 items down on the troubleshooting list.
I have witnessed a bad ground effectively weld intake/exhaust valves and seats. Enough so to pull the seats out of the head when the rocker actuated the valve. This was on a big cube industrial engine with thousands of DC/CCAs. A SBO will bend push rods first and snap trunnions. The wet/dry compression test will show valve train/piston ring problems. As will a leak down test.
My money is on breached ignition wires primary(small gauge) and/or secondary (plug wires). Open the hood in the dark, engine running, looking for arcing from breached ignition parts, wires, cap etc...
Then pull one plug wire at a time while its idling. No idle change = bad. Change = good. This will narrow it down to the problem cylinder/wire/plug etc...
Its possible the short from the questionable starter install heated up something to red hot. The ignition wires were touching metal somewhere and breached/melted the plug wire.
Also may have melted a hole in the exhaust head pipe? When 800+/- amps wants to find ground it will cause destruction.
Check all the above items before thinking about engine surgery.
Always start simple. Intake removal would be at least 10-15 items down on the troubleshooting list.
I have witnessed a bad ground effectively weld intake/exhaust valves and seats. Enough so to pull the seats out of the head when the rocker actuated the valve. This was on a big cube industrial engine with thousands of DC/CCAs. A SBO will bend push rods first and snap trunnions. The wet/dry compression test will show valve train/piston ring problems. As will a leak down test.
My money is on breached ignition wires primary(small gauge) and/or secondary (plug wires). Open the hood in the dark, engine running, looking for arcing from breached ignition parts, wires, cap etc...
Then pull one plug wire at a time while its idling. No idle change = bad. Change = good. This will narrow it down to the problem cylinder/wire/plug etc...
Its possible the short from the questionable starter install heated up something to red hot. The ignition wires were touching metal somewhere and breached/melted the plug wire.
Also may have melted a hole in the exhaust head pipe? When 800+/- amps wants to find ground it will cause destruction.
Check all the above items before thinking about engine surgery.
Thread Starter
Registered User
Joined: Mar 2014
Posts: 23
From: Vienna, AT
Thanks for these thoughts! I figure you might be interested in more facts about the electrical trouble - it also puzzles me ever since it happened. As I said I think myself capable of overhauling a starter, and I cannot imagine a professional shop going wrong when installing it. Also, it worked for a while...
Apart from the ground wire leading from the starter mounting screw to the frame the whole taillight and fuel gage wiring harness beneath the tailgate was melted down. So I am not sure whether the problem STARTED in the engine compartment or in the rear of the vehicle. The starter might not have been at fault initially after all. I´ll never find out. Anyhow, things got so hot that plastic pieces on the starter melted. The brake booster as well as the main brake cylinder were destroyed, as was the alternator. Plus some aftermarket temp and oil pressure gauges I had installed. The latter actually sent flames into the passenger compartment when the oil inside it was burning. So yes, I am glad I wasn`t on-site when it happened. But now back to the issue: I put in new spark plugs, wires and distributor cap. The exhaust headers seem to have survived. The unit of measurement I stated for compression where in bar. I have to admit I am not quite sure what the OEM specs are, however, the deviation on cylinders 5 and 7 from the rest (5,5 compared to > 8) is certainly not within specs. The speed/rate of the noise is certainly proportional to engine RPM. The volume/intensity at idle RPM increases with engine temp. Interestingly, it is louder in gear (lower idle RPM) than in Park (=higher idle RPM). While driving or accelerating, the volume increases with engine load (and also gets worse as the engine warms up). I will try the pulling-individual-plug-wires-test as well as the engine stethoscope to further narrow down the issue.
Apart from the ground wire leading from the starter mounting screw to the frame the whole taillight and fuel gage wiring harness beneath the tailgate was melted down. So I am not sure whether the problem STARTED in the engine compartment or in the rear of the vehicle. The starter might not have been at fault initially after all. I´ll never find out. Anyhow, things got so hot that plastic pieces on the starter melted. The brake booster as well as the main brake cylinder were destroyed, as was the alternator. Plus some aftermarket temp and oil pressure gauges I had installed. The latter actually sent flames into the passenger compartment when the oil inside it was burning. So yes, I am glad I wasn`t on-site when it happened. But now back to the issue: I put in new spark plugs, wires and distributor cap. The exhaust headers seem to have survived. The unit of measurement I stated for compression where in bar. I have to admit I am not quite sure what the OEM specs are, however, the deviation on cylinders 5 and 7 from the rest (5,5 compared to > 8) is certainly not within specs. The speed/rate of the noise is certainly proportional to engine RPM. The volume/intensity at idle RPM increases with engine temp. Interestingly, it is louder in gear (lower idle RPM) than in Park (=higher idle RPM). While driving or accelerating, the volume increases with engine load (and also gets worse as the engine warms up). I will try the pulling-individual-plug-wires-test as well as the engine stethoscope to further narrow down the issue.
Thread Starter
Registered User
Joined: Mar 2014
Posts: 23
From: Vienna, AT
There ist no visible Problem here, I have checked. But how can I measure lift? I assume that can only be done with the engine not runnning - thus with no oil pressure present. Will the lifters still die their Thing then?
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