Tim's 951 Rebuild
04-23-2014, 12:34 PM
#16
Pro
Thread Starter
You can find the tolerance group etched on the top of the piston, and a corresponding number stamped on the block. The cylinder bore looks OK for a street engine to me, but the piston is toast. Before you remove the pistons, remove the carbon from the top of the bore, or the rings will be ruined when you remove them. This will be controversial, but if the rings are within tolerance, I would reuse them. I have re-ringed two engines without polishing the bores, one was successful and the rings never seated in the other one. Plenty of others have had no trouble, but I am never lucky with this kind of thing. The nikasil coating is very nice, but it is sort of expensive if done correctly.
You will get many different opinions on what to do next. If the bores are within spec. I would have them polished with the special paste and install fresh rings. If the bores are out of spec. you have some decisions to make. The piston pin bushings are probably worn and need replacing as well.
The sediment in the oil cooler cavity looks like the coolant was not changed regularly. Not too surprising considering some of the other "repairs" the PO made.
If you can find a used engine known to be in good condition, that is probably the quickest and least expensive route to take. If you can find one with good compression and leak down numbers...
You will get many different opinions on what to do next. If the bores are within spec. I would have them polished with the special paste and install fresh rings. If the bores are out of spec. you have some decisions to make. The piston pin bushings are probably worn and need replacing as well.
The sediment in the oil cooler cavity looks like the coolant was not changed regularly. Not too surprising considering some of the other "repairs" the PO made.
If you can find a used engine known to be in good condition, that is probably the quickest and least expensive route to take. If you can find one with good compression and leak down numbers...
04-24-2014, 10:28 PM
#17
Pro
Thread Starter
Cleaned the block. Effin coldest, wettest thing I have ever done. Sprayed that engine cleaner goop on and then pressure washed it. Wasn't the easiest thing. And the water seems to always just spray right back at me. Fn whatever. Here is before and after
Would have been easier if I had used hot water. Now I am noticing a crusty beige substance caked on the outside of the cylinders where the coolant flows
Would have been easier if I had used hot water. Now I am noticing a crusty beige substance caked on the outside of the cylinders where the coolant flows
04-25-2014, 07:52 AM
#20
Rennlist Member
i have been there plenty of times.... just take it to a machine shop. and have them steam clean it. $35.00... I have the same engine stand. Like e30.. i have an e30 as well lol. there are some places around you.
04-25-2014, 09:00 AM
#21
Pro
Thread Starter
Word... i really don't want to take a cold shower outside again. That was miserable and i'm sure my neighbors got a good laugh too. Love the e30, it a bulletproof car too. I have put it through its tests. North country winter to southwest texas heat and roads. Took it 26 miles down a dirt road and practically a mile of rock crawling on that road. It desperately needs servicing though. I've kept up on the oil, but not anything else and belts have another 5-10k on them. I'll stop the digression. I'll look for a machine shop.
04-26-2014, 08:02 AM
#22
Pro
Thread Starter
Cleaned one more time with the engine gel degreaser and this time with hot water going into the pressure washer. Looks like somewhere along the line, they used a stiff steel brush on the aluminum machined surface on the front. I'll get that flattened and possibly the top flattened too.
04-26-2014, 12:37 PM
#23
Pro
Thread Starter
And it's off to the machine shop. He said probably 200 bucks to clean it more and machine the top and front. Any words of advice to pass on? I put the bearings back in the girdle and tightened the bolts down to get a proper alignment on the girdle and block. It didnt seem like the girdle wanted to align perfectly with the block even with the bearings installed. I would never forgive myself if they machined it like it is and then it turns out it was good enough before
05-01-2014, 12:15 PM
#24
Three Wheelin'
I would have him measure the bores before I spent anymore money. For whatever reason, the girdle and block do not mate up flush and have to be worked on to get flush. I use an oilstone, but it takes a loooong time. Decking the block is a good idea.
05-01-2014, 12:26 PM
#25
Pro
Thread Starter
Could you elaborate? I noticed the girdle and block weren't flush in the front where the oil pump mounts. Is there some other alignment needed other than the bearings and that one alignment dowel?
05-01-2014, 12:51 PM
#26
Rennlist Member
And it's off to the machine shop. He said probably 200 bucks to clean it more and machine the top and front. Any words of advice to pass on? I put the bearings back in the girdle and tightened the bolts down to get a proper alignment on the girdle and block. It didnt seem like the girdle wanted to align perfectly with the block even with the bearings installed. I would never forgive myself if they machined it like it is and then it turns out it was good enough before
05-01-2014, 01:01 PM
#28
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Thread Starter
05-01-2014, 02:06 PM
#29
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Don't get the block 'machined' on the front. The oil pump mounting surface does not line up if you just bolt the crank girdle in place - there is a procedure to follow to get it to fit. While the scratches on the surface are not want you really want - the factory recommended Loctite product will seal them up just fine.
If you just bolt it on and then machine the front it will not be correct. In addition the shop would have to pull every stud on the front to do it right - and I'll bet half of the shear off flush with the block!
Since you have pulled all the head studs skimming the top is not a bad idea - as long as its as minimal a skim as possible.
If you can find a shop with a baking soda blaster that is the best way to clean a block.
You should plan on pulling out all the oil galley freeze plugs to clean the oil galleys (get the oil galley brush set from summit/jegs).
Used pistons are easy to find. Alusil coated Wossners are just a phone call away...
If you just bolt it on and then machine the front it will not be correct. In addition the shop would have to pull every stud on the front to do it right - and I'll bet half of the shear off flush with the block!
Since you have pulled all the head studs skimming the top is not a bad idea - as long as its as minimal a skim as possible.
If you can find a shop with a baking soda blaster that is the best way to clean a block.
You should plan on pulling out all the oil galley freeze plugs to clean the oil galleys (get the oil galley brush set from summit/jegs).
Used pistons are easy to find. Alusil coated Wossners are just a phone call away...
05-01-2014, 03:08 PM
#30
Pro
Thread Starter
Don't get the block 'machined' on the front. The oil pump mounting surface does not line up if you just bolt the crank girdle in place - there is a procedure to follow to get it to fit. While the scratches on the surface are not want you really want - the factory recommended Loctite product will seal them up just fine.
If you just bolt it on and then machine the front it will not be correct. In addition the shop would have to pull every stud on the front to do it right - and I'll bet half of the shear off flush with the block!
Since you have pulled all the head studs skimming the top is not a bad idea - as long as its as minimal a skim as possible.
If you can find a shop with a baking soda blaster that is the best way to clean a block.
You should plan on pulling out all the oil galley freeze plugs to clean the oil galleys (get the oil galley brush set from summit/jegs).
Used pistons are easy to find. Alusil coated Wossners are just a phone call away...
If you just bolt it on and then machine the front it will not be correct. In addition the shop would have to pull every stud on the front to do it right - and I'll bet half of the shear off flush with the block!
Since you have pulled all the head studs skimming the top is not a bad idea - as long as its as minimal a skim as possible.
If you can find a shop with a baking soda blaster that is the best way to clean a block.
You should plan on pulling out all the oil galley freeze plugs to clean the oil galleys (get the oil galley brush set from summit/jegs).
Used pistons are easy to find. Alusil coated Wossners are just a phone call away...