RE-built engine only lasted 50 miles!
RE-built engine only lasted 50 miles!
Hi,
I'm at a loss to what I did wrong.
Rebuilt my engine with new bearings, cam, rings, honed cylinders, shimmed oil pump. Now, after its first long run to a show, the big ends are totally destroyed.
My first thought was oil pump, I had 35 psi when I first ran it, but when I put it back in the car, I only had the idiot light as a guide. (Monza)
I have just put a drill on the pump and am getting oil out of the bearing journals, obviously falling out now as the gaps are so big, but there isn't a blockage.
By the time it broke down, highway speeds, ahough i didn't go above 55 as i was running the rings in and much of it was slower as our motorways in England usually resemble a car park anyway, the oil was smoking well, so it got really hot. I used 10-30 oil so it should have been fine.
I have a new crank on the way as the old one was -20thou and I can't see the extra 10 getting rid of the scoring.
Any ideas what I might have missed? I don't want to trash it a second time. This is getting expensive.
Kev
I'm at a loss to what I did wrong.
Rebuilt my engine with new bearings, cam, rings, honed cylinders, shimmed oil pump. Now, after its first long run to a show, the big ends are totally destroyed.
My first thought was oil pump, I had 35 psi when I first ran it, but when I put it back in the car, I only had the idiot light as a guide. (Monza)
I have just put a drill on the pump and am getting oil out of the bearing journals, obviously falling out now as the gaps are so big, but there isn't a blockage.
By the time it broke down, highway speeds, ahough i didn't go above 55 as i was running the rings in and much of it was slower as our motorways in England usually resemble a car park anyway, the oil was smoking well, so it got really hot. I used 10-30 oil so it should have been fine.
I have a new crank on the way as the old one was -20thou and I can't see the extra 10 getting rid of the scoring.
Any ideas what I might have missed? I don't want to trash it a second time. This is getting expensive.
Kev
Re: RE-built engine only lasted 50 miles!
Looks like there was no oil film in the bearings? Did you check the bearing clearance with plastigage during your rebuild?
'61 140 PG Rampside
'66 Rear Alum V8 4-dr
'60 Monza PG coupe (sold, sniff, sniff)
'66 Corsa Fitch Sprint Conv. (First car 1971, recently repurchased)
'66 Rear Alum V8 4-dr
'60 Monza PG coupe (sold, sniff, sniff)
'66 Corsa Fitch Sprint Conv. (First car 1971, recently repurchased)
Re: RE-built engine only lasted 50 miles!
Hi,
Yes I did with the old ones, which were OK, but I decided to change them anyway, I didn't remeasure with the replacements. The only possibility is that although I ordered 20thou and I can see the big end bearings are, I can't check to confirm the mains were actually 20thou, yet. If I was sent the wrong ones then maybe I was loosing pressure there?
The other thing is, it was fine with little wear on the old bearings, and in theory I replaced like for like. So don't think it is that.
Yes I did with the old ones, which were OK, but I decided to change them anyway, I didn't remeasure with the replacements. The only possibility is that although I ordered 20thou and I can see the big end bearings are, I can't check to confirm the mains were actually 20thou, yet. If I was sent the wrong ones then maybe I was loosing pressure there?
The other thing is, it was fine with little wear on the old bearings, and in theory I replaced like for like. So don't think it is that.
Re: RE-built engine only lasted 50 miles!
That's unfortunate
Not sure what "shimming" the oil pump means. There are different gasket thicknesses for the pump endplate clearances. I always use plastigauge to check the end plate to gear clearance.
If the oil light did not come on then there should have been adequate oil pressure (if the oil switch and light works).
A few things come to mind.
The oil was not flowing through the oil cooler and overheated.
The end housing gasket was defective causing a lack of oil to the bearings. I once read a post of a gasket with one hole that was NOT cut in the gasket causing problems.
There was debris in the oil.
The block end gallery plugs (bellhousing end) came loose.
The crank main bearings and oil passages did not line up.
Oil passages in crankshaft were plugged up.
Did you plastigauge the bearings? If they were too tight you'd get this type of damage.
Not sure what "shimming" the oil pump means. There are different gasket thicknesses for the pump endplate clearances. I always use plastigauge to check the end plate to gear clearance.
If the oil light did not come on then there should have been adequate oil pressure (if the oil switch and light works).
A few things come to mind.
The oil was not flowing through the oil cooler and overheated.
The end housing gasket was defective causing a lack of oil to the bearings. I once read a post of a gasket with one hole that was NOT cut in the gasket causing problems.
There was debris in the oil.
The block end gallery plugs (bellhousing end) came loose.
The crank main bearings and oil passages did not line up.
Oil passages in crankshaft were plugged up.
Did you plastigauge the bearings? If they were too tight you'd get this type of damage.
Re: RE-built engine only lasted 50 miles!
Always assume new parts are INCORRECT. They rarely are, but the time you don't check is when they are bad! If the main crank bearings are too big they would have caused low oil pressure to the conrod bearings. Time to split the block and look at the mains. I once dismantled an engine with a crank cut 10thousands and the main bearings were correct, but someone had installed std. conrod bearings. Ruined the bearings and crank, but it did run!!Kevster wrote:Hi,
Yes I did with the old ones, which were OK, but I decided to change them anyway, I didn't remeasure with the replacements. The only possibility is that although I ordered 20thou and I can see the big end bearings are, I can't check to confirm the mains were actually 20thou, yet. If I was sent the wrong ones then maybe I was loosing pressure there?
The other thing is, it was fine with little wear on the old bearings, and in theory I replaced like for like. So don't think it is that.
Re: RE-built engine only lasted 50 miles!
Hi,
By shimming I meant, chose the right thickness gasket.
The oil certainly overheated as it burnt and black, but don't know if that was the cause or symptom of the heat from the bearing disintegrating? So oil cooler could be possible. It wasn't blocked as I cleaned it out, maybe the adaptor or the bypass valve, but that appeared to be ok.
I don't think it is the gasket or valley plug or passages as I can see oil reaching the journals now when I run the pump with a drill.
The bearings being too tight could be it. Yes the old clevite bearings had a plastigage gap within spec, but I changed them for new Clark ones as a precaution and didn't remeasure. Maybe they were a bit tighter?
I really can't remember if I checked the back of the main bearings for size, I have already checked my invoice and know I ordered correctly. In some ways I hope it is that as at least I can make sure I don't get a repeat!
By shimming I meant, chose the right thickness gasket.
The oil certainly overheated as it burnt and black, but don't know if that was the cause or symptom of the heat from the bearing disintegrating? So oil cooler could be possible. It wasn't blocked as I cleaned it out, maybe the adaptor or the bypass valve, but that appeared to be ok.
I don't think it is the gasket or valley plug or passages as I can see oil reaching the journals now when I run the pump with a drill.
The bearings being too tight could be it. Yes the old clevite bearings had a plastigage gap within spec, but I changed them for new Clark ones as a precaution and didn't remeasure. Maybe they were a bit tighter?
I really can't remember if I checked the back of the main bearings for size, I have already checked my invoice and know I ordered correctly. In some ways I hope it is that as at least I can make sure I don't get a repeat!
Re: RE-built engine only lasted 50 miles!
I would think you could overheat the oil if the cooler was blocked without the head temp light coming on as that is fair
Y well cooled by the air?
Y well cooled by the air?
Re: RE-built engine only lasted 50 miles!
When you pull out the crank, post a pic of the journals. If they aren't bad then either oil wasn't getting to the conrods or the main bearing clearance was so great as to reduce oil pressure to the conrod bearings.
Yes Plasitgauging the crank and rods is a PITA, but the time spent is well worth it to avoid a major failure. Even when I mic everything I still double check with Plastigauge.
BTW - If the replacement crankshaft is not turned, then have the crankshaft journals polished before installing new bearings to make sure it is the correct size. A "dirty" crank journal can easily be a few thousands too large. Metal from the bearing can accumulate on the crankshaft journal.
Yes Plasitgauging the crank and rods is a PITA, but the time spent is well worth it to avoid a major failure. Even when I mic everything I still double check with Plastigauge.
BTW - If the replacement crankshaft is not turned, then have the crankshaft journals polished before installing new bearings to make sure it is the correct size. A "dirty" crank journal can easily be a few thousands too large. Metal from the bearing can accumulate on the crankshaft journal.
Re: RE-built engine only lasted 50 miles!
Lack of lubrication to the rods. Could be wrong size bearings or any number of things, just have to look for the cause.
Re: RE-built engine only lasted 50 miles!
A good cause of your oil being "burnt" would be if your bearing clearances were too tight, and that is where you got your added friction from. But by the blued color of that crankshaft, it would almost look like you spun a bearing(s), with the color, and the deep gouges that are in it. Spun bearings usually come from too loose bearings, that end up overlapping one another.
Whatever you did, I would say, your clearances ended up too tight, and that is how you killed your engine. You always, ALWAYS need to check that, even when you have a crank turned down, and you get the corresponding set of bearings to match, you MUST check to clearances to be sure.
You need to look into the bottom end for sure. Remember also, Your oil passages are full of bearing and crankshaft grindings that have got to be flushed out of the oil passages and all through your engine. It almost is going to take pulling your engine and doing a very thorough cleaning to get all the crap out.
Whatever you did, I would say, your clearances ended up too tight, and that is how you killed your engine. You always, ALWAYS need to check that, even when you have a crank turned down, and you get the corresponding set of bearings to match, you MUST check to clearances to be sure.
You need to look into the bottom end for sure. Remember also, Your oil passages are full of bearing and crankshaft grindings that have got to be flushed out of the oil passages and all through your engine. It almost is going to take pulling your engine and doing a very thorough cleaning to get all the crap out.
Rusty in NC
Re: RE-built engine only lasted 50 miles!
I have the engine out but not stripped down yet.
The first thing I have noticed is the oil cooler had very little oil in it and the top return passage on the adaptor block is spotlessly clean. Now, it may just have drained down, but it seems too clean, the cooler isn't blocked as I can blow through it, but I'm wondering if the return passage is either blocked?
I don't think the bearings spun as the first two I took of were still in the correct position, but it is either extremely hot oil that lost all its lubricating property or no oil at all.
Thanks for all your suggestions and advice, soon have it apart, then I will update you on what we have. Replacement crank should be here by the too.
Thanks
Kev
The first thing I have noticed is the oil cooler had very little oil in it and the top return passage on the adaptor block is spotlessly clean. Now, it may just have drained down, but it seems too clean, the cooler isn't blocked as I can blow through it, but I'm wondering if the return passage is either blocked?
I don't think the bearings spun as the first two I took of were still in the correct position, but it is either extremely hot oil that lost all its lubricating property or no oil at all.
Thanks for all your suggestions and advice, soon have it apart, then I will update you on what we have. Replacement crank should be here by the too.
Thanks
Kev
Re: RE-built engine only lasted 50 miles!
Loose clearances affect oil pressure and can cause oil consumption issues because of the excessive oil bleed off that can overwhelm cylinders but they will not cause bearings to fail and spin.
Tight clearances are what kills bearings. Spinning is typically a result of the bearing crush being lost. Look on the back side of the bearings. If the locating tangs are still there, then they did not spin.
Tight clearances are what kills bearings. Spinning is typically a result of the bearing crush being lost. Look on the back side of the bearings. If the locating tangs are still there, then they did not spin.
1966 Corsa turbo
1969 Monza convertible
1987 Buick Grand National
1969 Monza convertible
1987 Buick Grand National
Re: RE-built engine only lasted 50 miles!
Right, finally had time to get in there.
So, 2 rods appear to have had their bearings spun. The crucial thing here is, the worst one that has worn through, measures 2 thou out of round on the Conrod, strangely under size inline with the rod.
The main bearings appear to have only suffered because of the overheated oil, and bits of bearing floating around. Now, there are a couple of learning points here, first is, if it ain't broke, don't try and fix it, (old English proverb for people who can't help pulling things apart). The bearing that were in there when I stripped it down were fine and had obviously worn in line with the change of end cap shape, so I should have left them alone, just thought, while I'm in there......
and secondly, despite me have built several engines before, with no problem, you must always plastigage the bearings, no question.
What do you think about my lifters, brand new with the cam, only done 50 miles, but they are stiff I'm the bore at the moment with grit, strip and clean them, or bite the bullet and buy new? So plan is, resize con rod and either polish or regained crank depending on state of new one when it arrives.
Thanks
Kev
So, 2 rods appear to have had their bearings spun. The crucial thing here is, the worst one that has worn through, measures 2 thou out of round on the Conrod, strangely under size inline with the rod.
The main bearings appear to have only suffered because of the overheated oil, and bits of bearing floating around. Now, there are a couple of learning points here, first is, if it ain't broke, don't try and fix it, (old English proverb for people who can't help pulling things apart). The bearing that were in there when I stripped it down were fine and had obviously worn in line with the change of end cap shape, so I should have left them alone, just thought, while I'm in there......
and secondly, despite me have built several engines before, with no problem, you must always plastigage the bearings, no question.
What do you think about my lifters, brand new with the cam, only done 50 miles, but they are stiff I'm the bore at the moment with grit, strip and clean them, or bite the bullet and buy new? So plan is, resize con rod and either polish or regained crank depending on state of new one when it arrives.
Thanks
Kev
Re: RE-built engine only lasted 50 miles!
I would open up several of the lifters and check for debris. You if no debris or damage you can clean and reassemble OR just replace them all.
1966 Corsa turbo
1969 Monza convertible
1987 Buick Grand National
1969 Monza convertible
1987 Buick Grand National
Re: RE-built engine only lasted 50 miles!
I tell you, reading this thread has me nervous as I prepare to start my rebuilt engine. I checked my bearings on the crank and found them to be almost universally on the tighter side of the mid range of the tolerance call outs. I was real happy with both the numbers and the consistency. But after seeing this, even though I am sure everything is fine, I am nervous about starting it up. Oh well we will have to wait and see.
Current owner
61(x2) Monza Cpe
55 Pontiac Chieftain Wagon
61 Progress here
https://www.facebook.com/pages/Chevrole ... 7898185672
https://www.facebook.com/pages/Goose-N6 ... 8869056897
61(x2) Monza Cpe
55 Pontiac Chieftain Wagon
61 Progress here
https://www.facebook.com/pages/Chevrole ... 7898185672
https://www.facebook.com/pages/Goose-N6 ... 8869056897
- bbodie52
- Corvair of the Month
- Posts: 11894
- Joined: Mon Aug 06, 2012 12:33 pm
- Location: Lake Chatuge Hayesville, NC
- Contact:
Re: RE-built engine only lasted 50 miles!
I doubt that anyone on this forum who has ever overhauled an engine did not suffer self-doubt and nervousness when first starting that engine! No matter how cautious and meticulous you think you were during the build, there is ALWAYS the fear that you overlooked something.
Exchanging information here on the Corvair Forum, and sharing stories of mistakes and failures as well as success stories helps us all to work toward the goal of zero defects as we work on our cars.
Exchanging information here on the Corvair Forum, and sharing stories of mistakes and failures as well as success stories helps us all to work toward the goal of zero defects as we work on our cars.
Brad Bodie
Lake Chatuge, North Carolina
1966 Corvair Corsa Convertible
Lake Chatuge, North Carolina
1966 Corvair Corsa Convertible