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  #1   IP: 69.95.215.30
Old 09-12-2010, 05:08 PM
Frank Frank is offline
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Bent push rods in new engine with 10 hours on it

I have 1988 Lurhs Alura twin inboards. It has 8 cylinder gas pleasure crafts. Engine on port side has 200 hours on it and very good. Last year The Starboard engine overheated from head gasket. Water was in the oil and engine was run unknowingly for several miles. I head east 60 miles out from Boston past Stellwagon so I did not want to take any chances. So, I purchased a rebuilt long block, complete gasket set, new exhaust manifolds, new risers. New Sherwood pump, new hoses ECT. I used the original intake manifold when installing the engine. After the engine was installed, Trip # I traveled 60 miles out and 60 miles back. I then changed the oil. Trip # 2- I traveled about 50 miles from Boston through the Cape Cod Canal to Westport, RI. Trip # 3-Traveled about five miles out and back. Engine was great, no issues. Two weeks later I went to the boat and the moment I started it, there was loud rapping sound. I shut it down right away and removed the oil fill cap and noticed # 5 rockers were loose. I started the engine again and I could see the rocker was loose.
I removed the valve cover and had two bent rods. I removed the intake and the exhaust manifold and took the head off. NOTICE: I cheated and only lifted the intake enough to remove the bad head. I never check the other head. The company that sold me the engine said that “water came back into the exhaust manifold and caused the smaller exhaust valve to freeze open”. I purchased a new head and returned to the boat and THEN I removed the intake off totally. It was then that I saw the other head also had bent rods. When we installed the engine the heads were already installed on it. We installed the exhaust manifolds. We followed instructions word for word including all torque requirements. All gaskets were installed correctly. I have new flaps on both exhaust manifolds. I have measured the angle of the engine compared to the “good” engine and it is an exact match in height and angle. The two new exhaust manifolds have rust at the same point where the rods bent. The rods of course are bent at the rear of the engine because of the angle of the engine. I checked the oil and it is a sludge mixture. We have been very careful when we did the engine install and the manifold install. Where did we go wrong? I cannot understand this. I know that the engine sales person is going to tell me that water came back and traveled 24” uphill and flowed back into the exhaust valves…this I promise. Also my exhaust is 6” above the water line when the vessel is moored. The gasket in between the riser and the manifold has not been checked as of yet however we checked this when we installed the manifolds and are positive they are the correct gaskets and installed correctly. I do not buy the story that sea water will travel past the new exhaust flaps then travel 8’ into the fiberglass muffler system and then travel uphill 24” and drop down into the exhaust ports. I looked at the exhaust manifolds and they look like they came off Noah’s Ark and they are only one year old. Did this happen because we never went back and did the re-torque the exhaust manifold bolts????? The exhaust gasket is also burnt and rusted at each location were the rods are bent. Any ideas anyone
Thank you
Frank
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  #2   IP: 199.173.225.33
Old 09-13-2010, 12:08 PM
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joe_db joe_db is offline
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Are you sure you are in the right place?
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  #3   IP: 71.118.13.238
Old 09-13-2010, 12:30 PM
Dave Neptune Dave Neptune is offline
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Talking 4 A-4's???

It is rare to get that much water back in while running and they wouldn't have time to rust into place anyway. I'd check the valve clearances. When in a marine application the clearances are very important as the engine is under a constant load (more heat on the exhaust side) and the valves especially the exhaust can stick from heat expansion. I have seen this when auto quality engines are placed into marine service. I have also seen many auto quality engines work fine however they (the re-mfg.) do give the extra clearance the exhaust valve requires, which also means (good for me as I make valve tooling) extra tooling on their part.
If you try a stock block from a re-manufacturer again try a truck engine as they usually pay a bit more attention to the concerns of heat due to the loads the engine will experience, but not always.
I could recomend 4 Atomic fours for reliability.

Dave Neptune
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  #4   IP: 216.115.121.253
Old 09-14-2010, 02:23 AM
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lat 64 lat 64 is offline
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I think your PCM v-8s are either a GM 350 or the venerable Ford 351W. The auto versions were hydraulic lifters(nob-adjustable) but I don't know what they do to the marinized kind.

Rust is sure a clear indicator of water. My first guess is a blown head gasket.
A good mechanic can see the evidence on the head from this.

Good luck with this. Glad you have two engines too.

russ
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