72 Post

Hi all. I'm new here and figured I'd throw out my first question. I have an all stock numbers matching 72 post with a 350 2bbl H motor. Just bought it last summer. Has 80K with the previous owner only driving it about 3K in the past 35 years. I had it at the mechanic to rebuild the carb as it had a flat spot on wide open throttle along with a hard hot start issue. While he was going over it he advised me that it has excessive oil blow by and is burning oil. He did a compression test and stated cylinder 7 was at about 105 psi and all others are 125-130. Being that the vehicle has sat so much would anyone recommend an additive such as Rislone compression repair with ring seal to possibly help? Or is this more of it's time to do an overhaul? Just looking for some good Oldsmobile advice. Thanks in advance, Mike.

don71

Welcome to the site Mike. I'd suggest driving the car and continue to enjoy it. Sure, try the engine supplement you suggested and see if it helps. It probably won't be a magic bullet but I don't see a need to tear it down at this time. You can plan ahead going forward,knowing at some point you can decide what to do in the off season with your time and budget. For now, put some miles on it and see how it goes.

Sugar Bear

Welcome!

Drive it for a while, with fresh oil and a fully warm engine push it hard uphill and let it coast down long hills to work the rings back and forth in the piston grooves, the rings may be stuck or clogged from sitting. Retest with the same gauge if possible and do a leak down test to determine if it is rings and/or valves. If it is rings I'd use a top end engine cleaner (SeaFoam, Marvel Mystery etc.) and put some of the solvent directly in that cylinder and let it soak overnight, drive it and retest again.

Good luck!!!

72 Post

Thanks for the suggestions everyone! I was thinking along some of these same lines but it is definitely comforting to hear someone else with the same thoughts.

joe_padavano

^^^THIS. Either do a leakdown test or the old-school test of a wet compression test to determine if the problem is rings or valves. While stuck rings on one cylinder is a possible situation, the more likely cause of a single cylinder being low is valves. Magic additives are unlikely to be a real solution, however.

72 Post

Thanks for the feedback. After further discussion with the mechanic he stated that all cylinders were around 105 with cylinder 7 and possibly 8 excessively soaking the spark plug with oil. (he wasn't the best experience and I won't be going back to him, unfortunately you learn the hard way). Quite a different scenario than I first described. On the flip side I drove it home tonight and it runs great! Hard to believe that it has these issues but than again it is almost 50 years old.

oldcutlass

Another thing to consider is if the engine has never had the timing set replaced, its probably time. Rislone is good for cleaning up sticky rings and minor lifter sticking issues.

Ozzie

Under the circumstances, it may be advisable to redo the compression test properly. The Olds service manual says that the lowest cylinder should be no less than 70% of the highest and no cylinder should be less than 100 PSI.