Lmackattack Posted February 16, 2011 Share Posted February 16, 2011 1977 285 tip turbine...Thinking about pulling the pan soon to check the rods and mains. Never had it off yet. Truck holds 30 psi of oil press at warm idle but it never gets above 45 psi when its warmed up running down the road at full RPM. Cold start it slowly comes up to 60 psi and never higher. just dont like that low of press as all the other macks I drove held about 55 psi running down the road. Will likely replace the oil pump while in there also. Wondering if the rear main seal can be replaced with the pan off? is it a 2 part seal. I cant recall and its been 10 years the last time I did a rear main. at that time the trans was off and the engine was apart... Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted February 16, 2011 Share Posted February 16, 2011 1977 285 tip turbine...Thinking about pulling the pan soon to check the rods and mains. Never had it off yet. Truck holds 30 psi of oil press at warm idle but it never gets above 45 psi when its warmed up running down the road at full RPM. Cold start it slowly comes up to 60 psi and never higher. just dont like that low of press as all the other macks I drove held about 55 psi running down the road. Will likely replace the oil pump while in there also. Wondering if the rear main seal can be replaced with the pan off? is it a 2 part seal. I cant recall and its been 10 years the last time I did a rear main. at that time the trans was off and the engine was apart...Dont we wish. No gota pull the trans. 1 Quote glenn akers Link to comment Share on other sites More sharing options...
Rob Posted February 16, 2011 Share Posted February 16, 2011 Dont we wish. No gota pull the trans.There is a carrier the seal rides in if memory serves bolted to the rear of the cylinder block.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
Lmackattack Posted February 16, 2011 Author Share Posted February 16, 2011 I was afraid of that. IMO the 2 part seals are junk...untill you need to replace a leaky one then they are nice that you dont have to pull the trans! LOL Quote Link to comment Share on other sites More sharing options...
Rob Posted February 16, 2011 Share Posted February 16, 2011 I was afraid of that. IMO the 2 part seals are junk...untill you need to replace a leaky one then they are nice that you dont have to pull the trans! LOLYour engine may still have a lead seal in the carrier, but I'm not certain.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
theakerstwo Posted February 16, 2011 Share Posted February 16, 2011 Your engine may still have a lead seal in the carrier, but I'm not certain.Rob I dont think so but here the thing about a lead seal. If its leaking it excessive blow/by. The oil is seal back with a slinger on the crank.If a lead seal is leaking it needs a over haul.When i worked for mack years back i remenber the forman had to show a few coustomers that by replacing with no help on the leak. Quote glenn akers Link to comment Share on other sites More sharing options...
Rob Posted February 17, 2011 Share Posted February 17, 2011 I dont think so but here the thing about a lead seal. If its leaking it excessive blow/by. The oil is seal back with a slinger on the crank.If a lead seal is leaking it needs a over haul.When i worked for mack years back i remenber the forman had to show a few coustomers that by replacing with no help on the leak.HI Glenn, yes I've heard that before also. Lead seals when fitted and installed correctly are the best there is, (my opinion). I don't know when Mack moved to a lip type seal but I assume in the mid 1970's. My 72 237 still had a lead seal as did my 75 283. Always though it was a neat idea to knurl the slinger grooves into the rear of the crank.Funny thing about that 237 engine is it had so much blowby the road draft tube was clogged by the combination of off road dirt, and oil mist from the engine being worn out. If you removed the oil fill cap from the engine with it idleing, you best have your face out of the trajectory path cause the crankcase pressure would relieve instantly and blow the cap about 20 ft. from the truck. Of course a vented fill cap would have left an oil slick wherever you went. I rebuilt that engine on the back porch of the house and had to have a wrecker come by to slide it into the truck.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
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