TTait
06-10-2011, 03:01 AM
I have my original engine on a stand now, and don't have a particular plan for rebuilding it. I'm not in a position to put a lot of money into it currently anyway, but here is the situation...
The engine had about 75k miles on it. It failed after installing a set of Don Stegers cams, which in itself were not the problem. It was pulled and replaced when a mechanic noted very poor compression. Upon pulling the heads after swapping the engine there are notable impact marks on all 6 pistons from the exhaust valves. It turns out that the mechanic who adjusted the valves after the cam swap never tightened the locking nuts on the valve adjusters, and they backed off and started colliding with the pistons.
Although the mechanic doing the assessment at the time said that I had probably blown seals at the bottom of the liners, it seems pretty clear to me that the exhaust valves got bent and that was the compression problem.
I'll have no problems per se having the heads looked over and valves replaced as needed, I have a good rebuilder locally for that.
Although its possible that I could just rework the heads and reassemble, I wouldn't know if it was right until I someday put it in a car, and that sounds like a terrific gamble.
I've attached a photo of a couple of the damaged pistons, all are similar. I have been told that trying to run the engine again with these pistons in this condition would lead to hot spots and cause a lot more trouble. I presume that a decent machine shop could polish/debur them, but I don't know if that would create a thinner spot on the piston that would eventually lead to more damage.
I purchased a spare set of used pistons a few years back on a lark, but I'm not clear on how to evaluate their condition.
The mechanic who pulled the engine also removed the heads at one point in the process, I have guarantee that he did it properly and/or that the bottom seals are still intact, so I assume those need to get done too.
Finally, the engine still has oil in it (2 years old but probably only 500 miles of use. The oil pan is leaking slowly and I'm assuming there is no reason not to drain out the rest of the oil now, even if I don't start the rebuild for a year or two.
My short term plan is then to drain the oil, spray a bit of WD40 onto the top of the pistons and perhaps into any water passage I can get at, and then try to work out how much needs to get replaced. I'm definitely a "while your in there" sort of guy and I'm not feeling rushed, but budget is currently a concern.
So...
How far to I go now (on a limited budget) on an exploritory disassembly so that I can work out a plan for what does and does not need to get done? What steps should I take to prevent any degradation of the engine from here forward.
If I had unlimited funds at this point I'd rebuild everything, and upgrade where I could. I'd consider a port and polish, I'd powdercoat, I'd have a long talk with Ed Uding about possibly upgrading to his higher compression pistons and or consider having the (original) cams milled down a bit. I'd consider looking at rebuilding it as a 3.0 - I'm open to upgrades in HP or reliability - just not budgeted for it.
Finally, If anyone has parts they feel I might need that they got in the past and now realize they will never actually use, let me know, maybe we can trade foe some other used parts I might have or something. I have some time (hopefully not too much) while temporarily unemployed to do some work on this, but little money.
So, suggestions? Questions?
Tom
PS - I know we have all lost sleep pondering this question: yes it is possible to get a prv off the floor of the garage and up onto an engine stand without a helper or a hoist:
Put a 2 x 4 under the back of the engine and use it as a fulcrum to lift the engine just enough to get a floor jack under it, its heavy but you can hold it with one hand and push the jack under with the other. Then roll the engine stand onto its side and bolt it up to the engine. Slowly raise the jack, I got enough lift to take the engine stand from sideways to just more than 45 degrees upright. At this point its high enough that you can easily pull the stand upright. Piece of cake - took 15 minutes and the wife didn't have to help
The engine had about 75k miles on it. It failed after installing a set of Don Stegers cams, which in itself were not the problem. It was pulled and replaced when a mechanic noted very poor compression. Upon pulling the heads after swapping the engine there are notable impact marks on all 6 pistons from the exhaust valves. It turns out that the mechanic who adjusted the valves after the cam swap never tightened the locking nuts on the valve adjusters, and they backed off and started colliding with the pistons.
Although the mechanic doing the assessment at the time said that I had probably blown seals at the bottom of the liners, it seems pretty clear to me that the exhaust valves got bent and that was the compression problem.
I'll have no problems per se having the heads looked over and valves replaced as needed, I have a good rebuilder locally for that.
Although its possible that I could just rework the heads and reassemble, I wouldn't know if it was right until I someday put it in a car, and that sounds like a terrific gamble.
I've attached a photo of a couple of the damaged pistons, all are similar. I have been told that trying to run the engine again with these pistons in this condition would lead to hot spots and cause a lot more trouble. I presume that a decent machine shop could polish/debur them, but I don't know if that would create a thinner spot on the piston that would eventually lead to more damage.
I purchased a spare set of used pistons a few years back on a lark, but I'm not clear on how to evaluate their condition.
The mechanic who pulled the engine also removed the heads at one point in the process, I have guarantee that he did it properly and/or that the bottom seals are still intact, so I assume those need to get done too.
Finally, the engine still has oil in it (2 years old but probably only 500 miles of use. The oil pan is leaking slowly and I'm assuming there is no reason not to drain out the rest of the oil now, even if I don't start the rebuild for a year or two.
My short term plan is then to drain the oil, spray a bit of WD40 onto the top of the pistons and perhaps into any water passage I can get at, and then try to work out how much needs to get replaced. I'm definitely a "while your in there" sort of guy and I'm not feeling rushed, but budget is currently a concern.
So...
How far to I go now (on a limited budget) on an exploritory disassembly so that I can work out a plan for what does and does not need to get done? What steps should I take to prevent any degradation of the engine from here forward.
If I had unlimited funds at this point I'd rebuild everything, and upgrade where I could. I'd consider a port and polish, I'd powdercoat, I'd have a long talk with Ed Uding about possibly upgrading to his higher compression pistons and or consider having the (original) cams milled down a bit. I'd consider looking at rebuilding it as a 3.0 - I'm open to upgrades in HP or reliability - just not budgeted for it.
Finally, If anyone has parts they feel I might need that they got in the past and now realize they will never actually use, let me know, maybe we can trade foe some other used parts I might have or something. I have some time (hopefully not too much) while temporarily unemployed to do some work on this, but little money.
So, suggestions? Questions?
Tom
PS - I know we have all lost sleep pondering this question: yes it is possible to get a prv off the floor of the garage and up onto an engine stand without a helper or a hoist:
Put a 2 x 4 under the back of the engine and use it as a fulcrum to lift the engine just enough to get a floor jack under it, its heavy but you can hold it with one hand and push the jack under with the other. Then roll the engine stand onto its side and bolt it up to the engine. Slowly raise the jack, I got enough lift to take the engine stand from sideways to just more than 45 degrees upright. At this point its high enough that you can easily pull the stand upright. Piece of cake - took 15 minutes and the wife didn't have to help