The Stovebolt Site Forums The Shop Area Engine Shop Rear Main?/ Leak- Forgot to mention...

This pertains to my "R.T.A.F. post:When I checked the radiator for over-heating,due to oil loss,radiator was "cold",(below 100 degrees F.),to the touch! This is after truck running highway speeds,for at least 20 minutes,and around town,30-45 M.P.h.,for another 1/2 hour,or so. Could this condition be caused by engine not venting correctly?? No coolant leaks,and engine was cool as well,(I could hold my hand on the valve cover,for a minute,without getting burned!) Engine sounded like it wanted to turn-over,but sounded like a high-compression engine cranking,("hot"),Just after I pulled over,and engine died. An hour or so later,engine started right up,and no rod/valve train Knock. I didn't run it long enough to check oil pressure,but it dropped to 20 P.S.I.,just before I shut 'er down. Thanks!

do you have a thermostat in?

Bill

New one installed 3 months ago. It's designed to stay "open",in case engine over-heats. Thermo. gauge registered "cold",even when I had the engine idling,and radiator was too hot to touch. That was when I adjusted the carb,and set the timing. No visible kinks in the gauge line,either.

never heard of one 'designed to stay open' when the water isn't hot or "just in case" - thermostats open as the water heats up, close as the water cools down - unless the 'design' was on your part and you wedged it open .... a stuck open stat can allow the coolant to move thru too fast and not take away enough heat .... and a gauge that reads cold when the rad is too hot to touch is defective, even if the sensor tube is OK

you need to get a laser thermometer and check various points on the engine and rad to see what's really going on, your first description sounds like a temperature problem, you can't run these old bolts around for an hour and have them still be 'cold', and if it wouldn't crank well until it sat for an hour it was too hot

Bill

The thermostat I bought is called "Safestat". It's designed to act normally,under normal conditions,but locks Open,if engine over-heats. Engine has been hard to start,(after warm-up), since I installed the H.E.I.Something's not right,that's for sure. Did I mention this is an S.C.O.,(no oil filter) engine? I'm debating on having the truck towed back to town,(about 35 miles),or drop the pan,(on site),change the seal,and pan gasket,and hope like crazy the plug behind the camshaft didn't blow. I'm going to check the downdraft tube for blockage,before buttoning it back up. Planning on installing a PCV valve,at the same time. I won't be able to work on it until Tuesday,but that's when the seal is expected to show up.Ordered,on the way. I was thinking about driving it back,and stopping every 5 miles,or so,and add a quart,just to get it home. Decided against the risk of spinning a bearing,or causing other further damage. It's a GREAT engine! Good compression,and ran GREAT,until the oil dump,out the rear of the pan! I'd rather fix the 261,than find and install a small block,or later 292. If I have to pull it,I'm definitely installing an oil filter! THANKS!

wetwilly5757,

Is the Safestat thermostat a Motorad Failsafe thermostat?
http://www.motoradusa.com/fail-safe-thermostat/

"When overheating occurs, fail-safe automatically locks in the open position to permit maximum coolant flow" Some people report that once it overheats it stays locked-open?

If it is not that thermostat, does the Safestat company have a website?

That's the one! Thanks for the clarification!

If it was my truck I wouldn't even consider dropping the oil pan to replace a rear main seal if the truck is 45 miles from my shop. I'd get it towed the 35 miles. I think that the chance of the seal just going bad all of a sudden is wishful thinking.
I would do some more diagnostics before tearing things apart. Maybe pull the distributor and use a drill to run the oil pump to get a better look to see if can find a source for the oil leak.

If the water was not touching the temp probe of the gauge, the gauge will read cold. The probe will only read water, steam or hot air will not make it read. Chances are, the engine was low on coolant, then over heated and locked the t-stat open. I have seen bus engines so hot the water was boiling in the block for 7 to 10 minutes and still read cool to normal temperatures on the gauge.

You would have to have one really bad rear main to go all at once like yours did. It could happen, but unlikely. Turning the oil pump with a drill will tell you pretty quick like Don suggests. Use some spray brake cleaner to really dry out the area before starting.

Don't go working on the side of the road, rear mains can be pain and should be done very carefully so you don't have the same problem later on.

Joe

I don't see the point in a thermostat like that. All thermostats stay open in an overheat condition. In fact they are always open after initial warm up if everything is working correctly.
If its cranking like that it means your timing isn't correct.

Timing's right on the dot,but I think the problem is a blockage in the crankcase ventilation system,which caused something to blow. More than likely,(as someone suggested in "R.T.A.F".),"oil plug behind the cam". No,i'm not going to try and fix this thing any time soon. The tow bill alone is going upwards of $200.00! It'll sit,(on my property), 'til funds are available. See Ya!