QuestionQUESTION: Hi. I am asking on behalf of my son but will give you all the details I know.
About 6 weeks ago, he acqured a 1976 Cheyenne. At that time, it needed a valve cover gasket but it has not been replaced yet. I dont know how frequently oil is needed. It has the small block 350 4bbl.
2 nights ago he called me for rescue saying the truck was losing power, wouldnt go above 40 mph and smelled like "something is cooking". He pulled to the side of the road and as he came to a stop there was a repetitious clanging sound (I worked in an auto shop 7 yrs and never heard a sound re-created quite like he tried to do) and then it stalled.
When I got there, I checked the oil. Wasnt showing on dipstick. Added 3 qts (but now its a quart over and thats not great I know). Temp guage read ok. We attempted to get it home from there (5-6 mi away) it would stay running without my foot on the gas. The humming of the motor grew increasingly loud and gradually slower (30 mph) there was no smoke. It stayed in 2nd or 3rd gear. It started to rattle from underneath and we pulled over again. There was a smell of antifreeze that I thought was coming from my truck but he said thats the cooking smell from earlier. We left it there til morning to cool off til morning.
6 hours later I went to get it, checked the radiator, water level was fine although the water was rusty buut not the worst I've seen. It started up fine, no smell but it still wouldnt idle withoit my foot on the gas. The oil pressure guage shot up to around 50. I was trying to get it home before it warmed up in case it was an overheating problem. For about 3-4 miles, it drove fine. As the engine warmed up, the oil pressure dropped and it became gradually slower and louder until the OP was between 5 and 10 and 30 mph was as fast as it would go. The clanging sound was back also. Pulled up in front of my house and coming to a stop, it stalled. No antifreeze smell, no repetitive clanging my son had heard before.
He started it up later that day for the neighbor to hear it and it soumded fine again, just wouldnt idle on its own. The only idea I can come up with is rod bearings or clearance. I hope ypu have other (cheaper) ideas. Any light you can shed on this would be very appreciated. Thank you.
Beth
ANSWER: HI BETH,WELL, THIS IS A GOOD ONE!!! JUST A GUESS,DOES THIS HAVE A CONVERTOR ON IT.IF SO I WONDER IF IT IS PARTIALLY PLUGGED CAUSING LACK OF POWER AFTER IT GETS WARMED UP.THIS WILL ALSO CAUSE IT TO GET HOT.DO YOU HAVE A VACUUM GAUGE ?? WE CAN CHECK FOR THIS !! THE OIL PRESSURE DROPPING BOTHERS ME..IF THE PRESSURE IS GOOD AT FIRST START UP AND THEN GETS LOW. THIS COULD BE FROM A FAULTY PUMP OR OIL RETURNS IN THE UPPER HALF OF ENGINE ARE PARTIALLY PLUGGED NOT ALLOWING ENOUGH OIL TO GO BACK INTO THE PAN TO THE OIL PUMP. MAYBE THE OIL PUMP PICK UP IS ALSO PLUGGING UP.. THIS IS JUST A GUESS. WOULD SUGGEST DROPPING THE OIL PAN AND HAVE A LOOK SEE..AS FAR AS THE NOISE GOES, I REALLY CAN ANSWER THAT ONE..BUT A LOWER END ROD NOISE IS LIKE RAP RAP RAP SOUND. YOU KNOW WHAT A LIFTER NOISE IS CLICK,CLICK,CLICK SOUND. KEEP ME UPDATED ON THIS,, WOULD LIKE TO HELP YOU OUT IF POSSIBLE. TRY TO ISOLATE THAT CLANGING NOISE,THIS WOULD HELP ME..
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QUESTION: I will check for a converter when I get back to the house, although it isnt running hot. I dont have a vacuum guage bit Im sure I know someone who does. Does Autozone loan something like that out? He reminded me last night there was also a hissing type of sound when pressing the gas that night. It was in park and he was havimg to stay on the pedal for it to keep running. The no idle thing didnt start until the truck shut off that night.
Its raining today but if it lets up, I will drop the oil pan. What would I be looking for?
Also, I dont know if its important or relavent but its been backfiring through the tailpipe since he got it
The guy who gave it to him said it has to do with the valve cover gasket. Cant remember how it relates to it. I can attempt to record the sound and if I can pinpoint its location, I'll take a video and point to the area its coming from
AnswerHI BETH,THE HISSING SOUND COULD BE FROM BIG VACUUM LEAK,WHICH WILL CAUSE A LOW IDLE TO STALLING PROBLEM OR A PLUGGED UP EXHAUST [SUCH AS CONVERTOR] I DO NOT KNOW ABOUT LOANING A TOOL OUT,I WOULD ASK A FRIEND. WHEN YOU DROP THE OIL PAN CK THE PICK UP SCREEN THAT IS TO THE OIL PUMP.SEE IF IT IS PLUGGED. THE SCREEN SHOULD BE CLEAN. REMOVE THE VALVE COVERS AND SEE IF THERE IS A LOT SLUDGE BUILD UP ON THE TOP OF THE HEAD PLUGGING THE OIL DRAINS..VALVE COVER GASKETS WILL NOT CAUSE A BACK FIRE,,JUST A OIL LEAK,,NO MORE THEN THAT..A BACK FIRE IN THE EXHAUST COULD BE FROM A FEW THINGS,STICKY VALVES,TIMING OFF, CARBURETOR NOT SET CORRECT,SPARK PLUGS FOWLED,FAULY DIST-CAP,,YOU GET THE IDEA..THIS MAY ALSO EXPLAIN WHY IT WONT IDLE AT A LOWER SPEED. GET BACK TO ME WHEN YOU KNOW MORE...TOM
