Ross
08-08-2006, 10:13 AM
A friends Olds V-8 has me puzzled with it's behavior.
This odyssey begins at purchase. A '70 442 convertible very pretty with a rough running motor, seemed a bit like an BAD ignition miss.
The seller said it was the W-30 camshaft making it rough, BS for sure. My friend has the hots for it and money burning a hole in his pocket so pays up.
Immediately trouble starts as when shut off the thing boils over. It seems to be running very hot all the time, the exhaust is like a blowtorch out the pipes and it reeks of preignition.
I started with an ignition tune-up and compression check, all semmed well but no improvement. At this point I began suspecting valvetrain trouble like a flat cam lobe so removed the rocker covers for a look. All the valves were opening, no measurements made. Next the timing gears were checked for alingment and wear, the marks were where they should be and the chain was fine. There was no # on the end of the cam to see what it is.
Another friend suggested a blown head gasket so the heads were removed and sure enough there was an area between two cylinders that was suspect and one valve showed evidence of coolant in that cyl. The compression check gave no clue to this. The heads were pressure checked and done at great expense with stellite seats and reinstalled this past weekend. The car runs exactly as before!!
Carburation is not an issue as the carb has been properly overhauled with the throttle rod bores bushed.The tune- up is right on and there are no vaccuum leaks.
This thing runs hot, shakes like a plug wire is undone, smells of preignition, blows coolant out the overflow when it heatsoaks and the exhaust is very very hot.
The head gasket seemed to make sense even though the car acted more like valvetrain problems. The hot exhaust could be attributed to steam, the smell perhaps from burning coolant and the "boiling" was maybe only the cooling system being pressurized.
This is one bitch of a car to take apart the top end on as it has a full load of accessories in the way. I'm getting disgusted and need some suggestions, my friend is counting on me and I don't want to just start throwing parts at it or take this fkr apart any more.
My latest suspicion is a wrong or poorly manufactured cam or timing set.
In thirty something years of amateur mechanics on
stuff from beaters to Formula 1 I've nver seen this. Somehow the sellers comment about the so called W-30 cam (the hot factory offering) leads me back to the valvetrain. I'll bet he installed some cam had these problems and is still pinching himself over the good fortune of selling this headache to my pal.
I'm out of ideas guys, so before I go and rip this monstous iron turd apart again someone please save me with an obvious simple solution I've overlooked.
I'm going to pressurize the cooling system on the off chance a head gasket is not sealing, and another comp. check. The plugs weren't run long enough to tell anything.
Ross
This odyssey begins at purchase. A '70 442 convertible very pretty with a rough running motor, seemed a bit like an BAD ignition miss.
The seller said it was the W-30 camshaft making it rough, BS for sure. My friend has the hots for it and money burning a hole in his pocket so pays up.
Immediately trouble starts as when shut off the thing boils over. It seems to be running very hot all the time, the exhaust is like a blowtorch out the pipes and it reeks of preignition.
I started with an ignition tune-up and compression check, all semmed well but no improvement. At this point I began suspecting valvetrain trouble like a flat cam lobe so removed the rocker covers for a look. All the valves were opening, no measurements made. Next the timing gears were checked for alingment and wear, the marks were where they should be and the chain was fine. There was no # on the end of the cam to see what it is.
Another friend suggested a blown head gasket so the heads were removed and sure enough there was an area between two cylinders that was suspect and one valve showed evidence of coolant in that cyl. The compression check gave no clue to this. The heads were pressure checked and done at great expense with stellite seats and reinstalled this past weekend. The car runs exactly as before!!
Carburation is not an issue as the carb has been properly overhauled with the throttle rod bores bushed.The tune- up is right on and there are no vaccuum leaks.
This thing runs hot, shakes like a plug wire is undone, smells of preignition, blows coolant out the overflow when it heatsoaks and the exhaust is very very hot.
The head gasket seemed to make sense even though the car acted more like valvetrain problems. The hot exhaust could be attributed to steam, the smell perhaps from burning coolant and the "boiling" was maybe only the cooling system being pressurized.
This is one bitch of a car to take apart the top end on as it has a full load of accessories in the way. I'm getting disgusted and need some suggestions, my friend is counting on me and I don't want to just start throwing parts at it or take this fkr apart any more.
My latest suspicion is a wrong or poorly manufactured cam or timing set.
In thirty something years of amateur mechanics on
stuff from beaters to Formula 1 I've nver seen this. Somehow the sellers comment about the so called W-30 cam (the hot factory offering) leads me back to the valvetrain. I'll bet he installed some cam had these problems and is still pinching himself over the good fortune of selling this headache to my pal.
I'm out of ideas guys, so before I go and rip this monstous iron turd apart again someone please save me with an obvious simple solution I've overlooked.
I'm going to pressurize the cooling system on the off chance a head gasket is not sealing, and another comp. check. The plugs weren't run long enough to tell anything.
Ross