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Hi friends. Over the winter I’ve noticed a puddle of antifreeze under the olds. I’ve located the leak on the engine but I’m not sure about what’s going on.
it appears to be leaking under the valve cover, but that doesn’t make sense so it must be lower. The bolt I’m pointing to in the pic seems to be very wet.
what am I looking at? What gasket could be leaking? The head? Must be, right? This is drivers side rear on a 303.
the car doesn’t consume coolant and there are no bubbles in the radiator.
Any thoughts? I’d like to tear into it before driving season.
Hi friends. Over the winter I’ve noticed a puddle of antifreeze under the olds. I’ve located the leak on the engine but I’m not sure about what’s going on.
it appears to be leaking under the valve cover, but that doesn’t make sense so it must be lower. The bolt I’m pointing to in the pic seems to be very wet.
what am I looking at? What gasket could be leaking? The head? Must be, right? This is drivers side rear on a 303.
the car doesn’t consume coolant and there are no bubbles in the radiator.
Any thoughts? I’d like to tear into it before driving season.
It seems a bit strange that there would be a puddle of anti-freeze while the vehicle consumes no coolant. You appear to be pointing to the rearmost cylinder head bolt. You could check the cylinder head bolts' "tightness" by using the tightening sequence shown in the shop manual. Torque is 65-70 foot-pounds. It could be that the head gasket is leaking coolant. The shop manual should detail a procedure for changing the gasket.
Likely the intake. Try retorquing the intake in proper sequence...inside to outside. You can go 5 lb/ft above the spec.
Check the hose clamps. Coolant has a higher propensity to leak at the joints in the cold winter...shrinkage
Pressure test the cooling system. See if it holds pressure. As part of the PSI test, I will pull the spark plugs as a safety to me just in case the coolant leaks into the cylinders and I forget and turn the key...don't want hydrolock while troubleshooting.
Keep an eye on the oil as far as its color. If you find milky coolant = deeper failure. Drop the oil just to see what comes out.
All great tips I plan to try. As mentioned, the engine does not consume coolant normally. This is the first I’ve seen the drip. I had the intake manifold off last year. I always follow the shop manual procedures. Could be that things have come loose. I’ll check torque.
no coolant in the oil. I’m glad it seems to be leaking out, not in. I’ll keep you all posted for posterity.
I also plan to keep you posted on a remote mount power brake booster I’ve installed. It seems to work fantastic. Time will tell how it all works on the road.
Likely the intake. Try retorquing the intake in proper sequence...inside to outside. You can go 5 lb/ft above the spec.
Check the hose clamps. Coolant has a higher propensity to leak at the joints in the cold winter...shrinkage
Pressure test the cooling system. See if it holds pressure. As part of the PSI test, I will pull the spark plugs as a safety to me just in case the coolant leaks into the cylinders and I forget and turn the key...don't want hydrolock while troubleshooting.
Keep an eye on the oil as far as its color. If you find milky coolant = deeper failure. Drop the oil just to see what comes out.
The intake manifold doesn't cover the rear two rear water jacket openings on the intake gasket surface. The drivers side may have a plate with a pivot point for the throttle linkage and pipe hole, the passenger side may have a blank plate, pipe plug, or bung. Both sides can leak at that point, run or drip down the back of the head, block, and on to the ground, and both sides attachment bolts are wet. The result is the smell of steaming evaporating coolant when hot and a slow drip when cold. The freeze plugs on the heads are also known to rust through, so check that rear plug seen between 5-7 spark plug, as well as the other plugs and drain valve on the block side, perhaps behind the starter. A head gasket leak to atmosphere would be a first time for me, never saw this happen on these engines ever.
7# radiator cap pressure is what is expected with our cars, I run a 5# cap locally available cataloged for the same vintage Chevy, and looks identical to Oldsmobile cap. If you don't want to pull it down right now to find the trouble, perhaps try some stop leak with the cap loose, then try it again with the cap tight. Over the years I have had old caps stick then not opening which stresses every part of the cooling system, so that merits a look as part of your examination. Some owners today want to add a 15# cap which is asking for trouble with these cars. There isn't one thing wrong using stop leak for a slow or sitting leak, Oldsmobile cataloged, used and recommended it's use, a workable repair expedient, at least until you can get to the bottom of the leak.
Last edited by coldwar; February 20th, 2022 at 06:39 AM.
Found the leak! As I often do, I overlooked the obvious and started looking for some big problem like a head gasket. Over the weekend I set up paper towels to find the leak. I couldn’t see the leak before because it would drip down onto the last cyl bolt. But the towel doesn’t lie!
thanks for the help. I’m sure I’ll need it all someday as I plan to drive the wheels off this Olds!
February 19th, 2022, 12:38 PM
