pyromanic Posted June 19, 2005 Share Posted June 19, 2005 So with conventional engines, say a small block Chevy, worn main bearings will result in low oil pressure. (amongst other things) What I would like to know is with these Soobs (EA 82) external oil pump, can an engine have worn mains and still show good oil pressure? In other words, is good to excellent oil pressure indicative of main bearing wear/lack of wear? Thanks Pyro Quote Link to comment Share on other sites More sharing options...
erik litchy Posted June 19, 2005 Share Posted June 19, 2005 im guessing its because theres only 3 main bearings instead? thats an excellent question Quote Link to comment Share on other sites More sharing options...
Alex C Posted June 19, 2005 Share Posted June 19, 2005 worn bearings will still produce low readings. The only vehicles where oil pressure is not affected by worn bearings is in roller bearing mains applications. Low pressure can also be caused by bad seals in the external pump on subarus. Alex Quote Link to comment Share on other sites More sharing options...
NorthWet Posted June 19, 2005 Share Posted June 19, 2005 worn bearings will still produce low readings... Nit, nit, nit... It is possible to have both worn bearings and "good" oil pressure, but it is because both indications are caused by same problem: Grunged/clogged oil passages. It is not uncommon for oil passages to get so grungy that they no longer flow properly, starving the main and rod bearings of oil while keeping the oil pressure up. Quote Link to comment Share on other sites More sharing options...
Alex C Posted June 20, 2005 Share Posted June 20, 2005 Ahh, good point, sorry I missed that. Alex Quote Link to comment Share on other sites More sharing options...
Ross Posted June 20, 2005 Share Posted June 20, 2005 If you have high oil pressure and worn bearings because of blocked oil passages, you will most likely notice considerable bearing noise. If you have good oil pressure, and a quiet, smooth engine, thats a fairly good indication of a good bottom end. Quote Link to comment Share on other sites More sharing options...
pyromanic Posted June 20, 2005 Author Share Posted June 20, 2005 If you have high oil pressure and worn bearings because of blocked oil passages, you will most likely notice considerable bearing noise. If you have good oil pressure, and a quiet, smooth engine, thats a fairly good indication of a good bottom end. Hmm. I don't really know what the heck I got. I have great compression. Zero oil leaks. Excellent oil pressure. And crank walk. (crank can be moved back to front a few thousandths) And I do indeed have a knock. It disapears at operating temp. This was supposed to be a new engine. And except for the knock, it seems like it is. A puzzle indeed. Why the heck would somebody do a rebuild and re-install a worn or defective thrust bearing? Oh well, it runs fine, so far. Pyro Quote Link to comment Share on other sites More sharing options...
RickOregon Posted June 20, 2005 Share Posted June 20, 2005 Nit, nit, nit... It is possible to have both worn bearings and "good" oil pressure, but it is because both indications are caused by same problem: Grunged/clogged oil passages. It is not uncommon for oil passages to get so grungy that they no longer flow properly, starving the main and rod bearings of oil while keeping the oil pressure up. That's what I was thinking, too. Are there any surefire methods to treat the engine that will unclog the oil passages? Short of removing the engine and blowing them out? Does a flush with diesel do any good? Any other cleaners/treatments you're aware of? -Rick Quote Link to comment Share on other sites More sharing options...
KStretch55 Posted June 20, 2005 Share Posted June 20, 2005 I've heard of some garages that do oil system flushes. I don't know what they use or how they do it, but they claim it's effective for cleaning the sludge and gunk out of the passages. You might check in your area and see if some do the same. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted June 20, 2005 Share Posted June 20, 2005 Maybe they didn't do anything with the mains. Is the knock a crank bearing or TOD? Or is it the crankshaft/flywheel hitting things due to end-play? I've had an engine (non-sube) with thrustbearing probs that the flywheel would hit the sheetmetal that spans the gap between the engine and tranny bottoms. Nothing can guarantee clean passages better than removal and physical cleaning and inspection. It depends on what is doing the clogging as to what particular products might do. If it is grit, nothing is really going to help, and do you want large chunks trying to squeeze past your plain-bearing surfaces? For everyday gunk, maybe some ATF, MMO, or Seafoam (which I haven't used yet). The ATF is high-detergent, I assume the MMO is solvent, and it sounds like Seafoam is solvent (based on the trans stuff I just bought). Quote Link to comment Share on other sites More sharing options...
KStretch55 Posted June 20, 2005 Share Posted June 20, 2005 Couldn't agree more. Most mechanics I've talked with say a flush usually knocks more stuff loose to get into the system than it cleans. Goes for engine oil or transmission. Quote Link to comment Share on other sites More sharing options...
RickOregon Posted June 21, 2005 Share Posted June 21, 2005 Yes, if there's something in the oil passages that could harm the engine, I'd say that would be true - worse to knock that stuff loose. But if the deposit is something that will dissolve with a solvent or diesel, and the oil passages are cleaner as a result, they'll be able to allow the flow of oil to where it's needed, and that's a plus. The reason I asked about diesel is that the maintenance manuals for our D-7 Cats recommend flushing the engine and transmission with diesel before adding new oil/gear oil - to remove deposits. Must do a pretty good job if it cleans out all the grunge in an old Caterpillar. I've followed this technique, and even though it takes a lot of diesel [transmission hold around 15 - 20 gallons!], it seems to flush out the systems pretty well. I've never used Sea Foam, but I've used Marvel Mystery Oil [MMO] on a few occasions. Old timers recommend it in the older airplane engines, and I've added it to the crankcase of our Cessna every now and then. Haven't yet tried adding diesel to the airplane oil though... LOL -Rick Quote Link to comment Share on other sites More sharing options...
breaffyaviation Posted June 22, 2005 Share Posted June 22, 2005 Your Subaru engine does not have thrust bearings or washers .The forward to back play you mention is caused by serious wear on your middle main bearing which has two side flanges that act as your thrust washers .This play suggests serious main bearing wear and no amount of flushing will help. Jude Quote Link to comment Share on other sites More sharing options...
pyromanic Posted June 22, 2005 Author Share Posted June 22, 2005 Your Subaru engine does not have thrust bearings or washers .The forward to back play you mention is caused by serious wear on your middle main bearing which has two side flanges that act as your thrust washers .This play suggests serious main bearing wear and no amount of flushing will help.Jude Yes. AND I have great oil pressure and compression. Pyro Quote Link to comment Share on other sites More sharing options...
NorthWet Posted June 22, 2005 Share Posted June 22, 2005 ...The reason I asked about diesel is that the maintenance manuals for our D-7 Cats recommend flushing the engine and transmission with diesel before adding new oil/gear oil - to remove deposits. Must do a pretty good job if it cleans out all the grunge in an old Caterpillar. I've followed this technique, and even though it takes a lot of diesel [transmission hold around 15 - 20 gallons!], it seems to flush out the systems pretty well. ... I would be REALLY careful about using an easily combustible material like diesel to clean out my engine or tranny. Leaving burnable fumes inside of the engine case in particular could be inviting explosion. The PCV system is meant to deal with this situation, but I wouldn't rely on it heavily. Quote Link to comment Share on other sites More sharing options...
Ross Posted June 22, 2005 Share Posted June 22, 2005 Diesel isn't much easier to combust than the mix of engine oil and petrol thats normally in there. I have heard of people getting a lot of Dirty crap out when they fill up the entire engine with diesel. Quote Link to comment Share on other sites More sharing options...
pyromanic Posted June 23, 2005 Author Share Posted June 23, 2005 Diesel isn't much easier to combust than the mix of engine oil and petrol thats normally in there. I have heard of people getting a lot of Dirty crap out when they fill up the entire engine with diesel. Folks have been flushing the internal combustion engines crankcase with diesl for ever. I don't believe anybod has ever been blown up. Never heard of one case. However, I don't do it. I think you gotta be way quick with this harsh treatment. Can destroy bearings very quickly, so I'm told and sounds logical to me. Think thers safer less harsh ways. But explosions? Don't think so. Pyro Quote Link to comment Share on other sites More sharing options...
RickOregon Posted June 24, 2005 Share Posted June 24, 2005 NorthWet - I understand your concern about combustion with diesel. Certainly a factor to consider. I'm thinking of running the engine at idle for a brief period after refilling with diesel. Then yanking it. Then inverting with an engine stand to get the diesel up into the top part of the engine for awhile then draining after awhile, then re-installing the engine and refilling with lo-viscosity oil or ATF to do another flush. Just a thought. The engine has high miles so if that work, great. If not, I'll swap. -Rick Quote Link to comment Share on other sites More sharing options...
Ross Posted June 25, 2005 Share Posted June 25, 2005 Ive never heard of running a motor with deisel in it - i don't think that would be a good idea. What i ahve heard that works well, is to completely fill the engine - including taking out spark plugs and filling there as well - and letting it sit for a while. Then drain it completely, (i presume you would have to turn the motor over by hand with teh spark plugs out to get the deisel out of there??) and apparently a fair amount of crap comes out. I doubt this would do much for clogged galleries or the like, but would probably be good for giving the engine a general clean out, and removing carbon deposits from the heads/pistons. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 25, 2005 Share Posted June 25, 2005 my friends dad looked at ME funny when i wouldn't fill my XT6 up with kerosene and run it for a few seconds. said he used to do it all the time!?!?!?? i think he was sniffing kerosene. Quote Link to comment Share on other sites More sharing options...
pyromanic Posted June 25, 2005 Author Share Posted June 25, 2005 my friends dad looked at ME funny when i wouldn't fill my XT6 up with kerosene and run it for a few seconds. said he used to do it all the time!?!?!?? i think he was sniffing kerosene. Really, the old timers (I will be one soon, or maybe I'm in denial?) used to use to run deisel or kerosene all the time as an engine flush. The key words in the above quote is probably "a few seconds". Take heed if you try it. "A few seconds". Still, I'm convinced there are safer ways. I don't mean safer in regards to explosions, just safer for your crank bearings. Also bear in mind that most if not all commercial engine flush treatments are "diesel like" or "kerosene like" products. This is pretty much indisputable. But don't they tell you to "add to" the oil in the crankcase? That's why they run some amount of miles, or an entire oil change duration, as aposed to "a few seconds", like the old times did with straight deisel or kerosene. Probably (I think) the best or at least the cheapest engine flush is add some ATF to crank case oil, but his has probably already been mentioned. But my problem seems to be that somebody did a complete re-seal and head job, and never touched the bottom end. (this is speculation) Hence great oil pressure, no leaks, runs strong, great compression, but it knocks. Crank walk. Very frustrating, as I was told by seller it had a new engine. Turns out not. Mostly new, but------how long will it run? It's a crap shoot. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.