Engine from Hell

[Doug L.]

I'm back with another problem. My car has been with a local Corvette shop, very experienced and highly recommended. I went in for setup of the FI unit, timing setup and a leaky front brake wheel cylinder. Prior to going in the engine was completely apart when we were trying to diagnose the problem of water in the #8 cylinder. There were no visible damages to any component when it was reassembled. Three weeks ago they were adjusting the FI unit. It sat in the garage overnight and when started the next morning it started making noise. The noise concerned them enough that they drained the oil and pulled the oil pan. They found a bent rod in the #7 cylinder. According to the shop there was no loud bang, just some unusual noise. They found no water in the oil when the pan was drained and said they found no trace of fuel either. My problem is trying to figure out what caused the bent rod. I don't have the piston out yet to see if there is more damage. The shop is leaning towards the "spider" of the FI unit. I would appreciate any theories on what could cause the connecting rod to bend. The FI unit was rebuilt by John D, but the spider is original and tested OK. The connecting rods are new Eagle rods. I would really like to have some idea of what the cause was before reassembling the engine. Any input will be greatly appreciated. Thanks-Doug

[Dick W.]

Re: Engine from Hell

It sounds like it definitely hydraulic'd bending the rod. Did you find the source of the water when you tore it down the first time?

[Michael H.]

Re: Engine from Hell

Doug,

Did you have the block bored over size at all ? I had a 65 327/365 that I had bored over .030 and I had water in two cylinders due to pin holes in the casting. What happened was the casting had shifted when it was poured so I did not have the same thickness in the walls all the way around. Your water probably went out the exhaust valve after it bent the rod and maybe that's why its not in the oil. Do a leak down on your cylinders and see what you find.

Mike

[Doug L.]

Re: Engine from Hell

I did. The head gasket which was replaced. The water problem was also on the opposite bank (#8 then, #7 now)

[Doug L.]

Re: Engine from Hell

Thanks. I'll try that. The block was bored and sleeved back to 4". We pressure tested the block when we had the problem with #8. It checked OK. We also magnafluxed and pressure tested the cylinder heads. When I had the water problem in #8 there was plenty of antifreeze-water in the oil. Pretty clear what was happening. I was out of the US when this latest problem occurred so don't know exactly what happened or whether they looked at the oil closely. I asked and they said they did and saw no evidence of water or antifreeze. If it was hydraulic lock from fuel, which is their theory, it seems that fuel would have been found in the oil. Unfortunately the oli is long gone.

[Edward J.]

Re: Engine from Hell

Doug, generally with a bent rod Its like Dick says hydro lock. coolant or fuel filled cylinder(s), likely coolant. To dump that much fuel is highly unlikely. My advice is that they should pull the spark plug for that cylinder and check for signs of anti freeze or fuel on plug tip. that should give you the evidence. There is nothing else I can think of.

Doug, Oil or fuel does not alway enter the engine crank case oil,If there was anti freeze or fuel in the cylinder there may still be evidence if you remove the exhaust manifold there maybe something hanging out for you to see. or like I said he spark plug tip.

[John D.]

Re: Engine from Hell

Doug, As mentioned before when the FI unit is the cause of engine failure there is typically evidence of gas in the oil.
It's too late now but if the dipstick was pulled to see if it smelled of fuel or to see if the oil level was higher.

Just doing a simple flow test on the FI unit when it's off the car is a test to see if the fuel injection is leaking or syphoning fuel.
It's a shame what you have gone thru with this engine but I know you will get it resolved.
But as mentioned above the problem may not be from fuel at all. Could be antifreeze causing the problem since this rod is on the other side of the block from your initial issue. You fixed the problem on #8 side but hopefully you don't have a similiar problem on the opposite side of the block.
If the problem is FI related there would have to be two failures in the unit.(at the same time) The anti-siphon check valve in the fuel meter would have to fail from being stuck in the open position. #2. The spider assembly check value would have to be stuck in the open position or in some cases the check valve needle (in the spider) might be leaking down.
Hard to believe both of those parts would take a dump at the same time. Now say it is the FI unit causing all the problems. The question then arises is just what caused the two FI check valves to fail. You put everything new in your car. Tank, fuel lines, fuel pump. But say some dirt got into the FI unit. That would definitely be a minus factor. I have seen 63 to 65 FI units with anti-freeze in the plenums. Now if that was the case I would say the next step might be hydraulic lockup.
More testing needed to find the cause. John

[Dan H.]

Re: Engine from Hell

Doug, one thing I recommend is to put an electric shut off valve in FI spider fuel supply line. I got mine from Ken Hanson, nice set up. Cured my 'wet # 8 spark plug' problems, probably saved my engine. #8 is dry now, car runs great! Whether or not this was your problem, incorporate it in your overall 'fix' of your problem.
Dan

[Don H.]

Re: Engine from Hell

I had hydro-lock in my '60 320 unit years ago - bent two rods and broke two pistons. Now I would not run a Rochester F.I. unit without an anti-syphon valve. When I assembled a 375 unit last year I installed the kit from Ken Hanson that Dan referenced above. As the saying goes, "fool me once, shame on you . . . etc." Good luck, Don H.

[Doug L.]

Re: Engine from Hell

Thanks for all the suggestions. I will get the car back next week and start disassembly. I have a lot of things to look for. My concern is that so much time has passed there may be no evidence left. I'll advise what I find.

[Joe R.]

Re: Engine from Hell

Doug,

I'm sorry to hear that you're still having problems with your engine. Bummer! For an article on how to avoid fuel hydrolock, check out page two of this newsletter:

http://www.stlouisncrs.org/news_files/St_LouisNCRS_ChapterNewsletter3rdQuarter2012.pdf#page2

Joe

[Doug L.]

Re: Engine from Hell

Thanks for the article Joe. I discussed this with JD last night. I'm hoping I can determine what caused it, water or fuel. If fuel, and maybe even if it wasn't, I'll probably add a check valve. Doug