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poorboy
09-11-2010, 02:55 PM
I have a 96 classic 22 with a 454 mag L29 block with stainless marine headers system. The motor is a Mercury Marine reman. from 2002 and with 73 hrs on it. The boat was not used from the 4 th of july to labor day and when it was started up, there was a dead miss on one of the cylinders. new plugs helped some but a water test revealed a problem. Further checking revealed that #3 plug had water droplets on it and the exhaust valve was found stuck open after a compression test. all other cylinders were 120. bore scope comfirmed the open valve. removal of the valve cover produced a broken pushrod for that valve also. Pulled the motor out of the boat today and removed the header/manifolds. and found salt/water slimy solution in each port of the manifolds on both sides and the outside exhaust ports of both heads were rusty and had water droplets in them and on the valve face. The center two ports were whitish in color with the #3 port being just about normal in appearance. It was evident that there has been a problem for some time. I have not used the boat for more than 4 hrs since purchase and it ran fine on a water test and the last time it was used on the 4 of july. tested the header manifolds with 40 lbs of water pressure and cannot fine a leak! Anyone have an idea on this one. My first thoughts are a header problem with too much cam but its mercury stuff as far as I know. It did idle nice and did not sound over cammed. I will remove the intake and heads next to see if that reveals anything else. What else could cause water in all of the cylinders?? I cannot figure where the water is coming from if not a header issue. I have not heard of such a problem with stainless marine':(

Barry Eller
09-11-2010, 07:42 PM
I have a 96 classic 22 with a 454 mag L29 block with stainless marine headers system. The motor is a Mercury Marine reman. from 2002 and with 73 hrs on it. The boat was not used from the 4 th of july to labor day and when it was started up, there was a dead miss on one of the cylinders. new plugs helped some but a water test revealed a problem. Further checking revealed that #3 plug had water droplets on it and the exhaust valve was found stuck open after a compression test. all other cylinders were 120. bore scope comfirmed the open valve. removal of the valve cover produced a broken pushrod for that valve also. Pulled the motor out of the boat today and removed the header/manifolds. and found salt/water slimy solution in each port of the manifolds on both sides and the outside exhaust ports of both heads were rusty and had water droplets in them and on the valve face. The center two ports were whitish in color with the #3 port being just about normal in appearance. It was evident that there has been a problem for some time. I have not used the boat for more than 4 hrs since purchase and it ran fine on a water test and the last time it was used on the 4 of july. tested the header manifolds with 40 lbs of water pressure and cannot fine a leak! Anyone have an idea on this one. My first thoughts are a header problem with too much cam but its mercury stuff as far as I know. It did idle nice and did not sound over cammed. I will remove the intake and heads next to see if that reveals anything else. What else could cause water in all of the cylinders?? I cannot figure where the water is coming from if not a header issue. I have not heard of such a problem with stainless marine':(


It is getting water in the engine somewhere. Blown head gasket, leaking riser gaskets, intake leaking or just the valve being open and sitting with water in the block. You are going to have to rebuild anyway or least a valve job...just make sure everything is correct going back together.

DonziJon
09-11-2010, 08:13 PM
If you had stock cast iron risers/elbows I would suggest a pinhole in the riser letting water into the exhaust manifolds and therefore into the cylinders.

My first encounter with this was at 190 hours since new. I think the port side is the first likely place. :lookaroun:

poorboy
09-11-2010, 08:17 PM
I agree with the valve job or hopefully not,possible rebuild. The header manifolds are blocked off in casting at the riser and all water to be discharged flows thru a hose coming out the top of the manifold and going into the front of the riser. A ring gasket at the manifold/riser meeting surface seals exhaust only on the stainless marine setup. The rectangle port intake manifold does have a exhaust cross over to warm the choke thermo if used and exhaust flows from #5 to #4 exhaust ports. That may have been how the water got from the stuck valve side (left) to the right side. Then like you said, a blown intake gasket or head gasket are possibles too. just would like to find the problem and be sure I fixed it before putting the motor back in. Tomorrow I will get a chance to take the heads and intake off and go from there. Thanks for the response!:yes:

poorboy
09-12-2010, 04:11 PM
Ouch! at 190 hrs you would not think of a riser problem yet. sounds like that may have been a casting issue. I had another 454 a few years ago start missing and it had low compression on #2 @ 60 lbs. The valve face was just starting to rust some and that was caused by the intake gasket leaking at the water passage next to #2. that motor had under 300 hrs on it but was an ocean deweller. I got the intake off today and found no sealer on the intake threads and something other than black RV was used for sealer at the front and back. what ever it was it had some holding power. All intake ports of the heads were moist. Heads come off tomorrow eve. I dumped the oil filter and no water was found there. The motor was a mercury reman. as indicated by a tag but the rocker arms are comp. cam. roller tips. which gives me the idea the original heads were used on a merc short block. If I don't find any sure signs of a problem I will have the heads magnafluxed to check for cracks. Thanks for the response.:yes:

mrfixxall
09-12-2010, 05:05 PM
on another note,BBC valve guides go through the water ports in the heads,may have some leaking into the ports..also if a exhaust valve was stuck open whyle runnning it will act like a vacume cleaner and suck water back into the engine..

poorboy
09-13-2010, 09:24 PM
Thanks Mr. Fixall, that comfirms my same conclusion of where all the water came from and a leaking valve guide may have caused the valve to stick in the first place. I've contacted the machine shop and they will check both heads out as soon as I can get them there. Is that a monte you restored in the pic.? I sold a restored 71SS a few yrs ago and presently restoring a 70 monte w/BB (not orig.)

mrfixxall
09-14-2010, 12:03 AM
Thanks Mr. Fixall, that comfirms my same conclusion of where all the water came from and a leaking valve guide may have caused the valve to stick in the first place. I've contacted the machine shop and they will check both heads out as soon as I can get them there. Is that a monte you restored in the pic.? I sold a restored 71SS a few yrs ago and presently restoring a 70 monte w/BB (not orig.)

Yes that is my first baby,, Its my first car, i bought it when i was 15 (1980)for $300..its a factory ls3 car, 1972 BBC 400 t 400 rear swaybay and rear boxed lower control arms, 12 bolt, buckets factory tach and guages..

Better pic here post 29

http://www.donzi.net/forums/showthread.php?t=61099&page=2

poorboy
09-14-2010, 09:02 PM
Real nice monte for sure and rare LS 3 BB. Super restore. My dad bought a brand new 72 monte SB and I always liked that car. I finally got it from him mid 80's and let it go 8 yrs later. bought the 71 SS 1/2 restored in 2000. It was classic copper and I changed the top from tan to black, LS5 454, auto, buckets, PW, etc. build sheet ralleye wheels. then I got a 67 Chevelle BB,RED 90% restored. finished it and the monte, came across an LS6 4 spd 70 Chevelle stored since 75 and sold the monte to restore the chevelle. never restored it and sold it a couple yrs ago and recently bought the donzi. Figured I could have more fun with the donzi then the 70 chevelle which would not have been driven much at all. Used the donzi 4 times now this. Always something! With little nice weather left in my area this may become a winter project and I'll just start the fall striper fishing alittle earlier with the other boat.

A2VeeDub
09-15-2010, 12:18 PM
My fathers boat (22C w/ 454 and stainless marine manifolds) had similar issues. He was running a little bit bigger cam though. He ended up adding extensions to the stainless risers to force the introduction of water into the exhaust further down the pipes. It got rid of about 95% of the problem.

poorboy
09-15-2010, 09:38 PM
Can you remember about how much he added? I guess it is not critical to add 4 inches or more, would just need to remove the riser if one needed to pull the motor. that is no problem compared to the water issue. The machine shop will pressure checks the heads and if nothing found then it must be the headers. I heard of another brand having that problem also, Thanks much for the info!:yes: I pulled the heads this eve and could not find any signs of a leak anywhere in the motor itself. all gaskets were good. Pistons and cylinder walls all good. Valve must have stuck hard from not being used for 60 days. Does anyone know how much the stainless headers help horsepower wise????

mrfixxall
09-15-2010, 10:14 PM
Can you remember about how much he added? I guess it is not critical to add 4 inches or more, would just need to remove the riser if one needed to pull the motor. that is no problem compared to the water issue. The machine shop will pressure checks the heads and if nothing found then it must be the headers. I heard of another brand having that problem also, Thanks much for the info!:yes: I pulled the heads this eve and could not find any signs of a leak anywhere in the motor itself. all gaskets were good. Pistons and cylinder walls all good. Valve must have stuck hard from not being used for 60 days. Does anyone know how much the stainless headers help horsepower wise????


Theirs a member here and oso,goes by the nams alecsammy..anyhoo he has a 22c with a 502 with the same exhaust and is having problems injesting water..He also extended the end of the riser's and is still having problems..The only thing i can think of in your situation is either the stuck valve caused the problem or mabe one of the exhaust flappers are letting water in when putting it in the water or sitting in the water when waves crash into the back of the boat??

A2VeeDub
09-16-2010, 11:13 AM
I dont remember exactly how much he added. I think it was around 3-4 inches.


mabe one of the exhaust flappers are letting water in when putting it in the water or sitting in the water when waves crash into the back of the boat??

Good point. I forgot to mention that he is running tips without any flappers at all. I tell him all the time he is crazy. After finding the salt in the ports the first time, he may have changed his driving style to reduce the chance of water coming back in at the same time he extended the risers. So I guess the reduction could be from either, but the extensions had to help some.

poorboy
09-16-2010, 10:21 PM
thanks for the measurement on the extensions for the risers. Right now planning on doing that as a precaution. My donzi is on a float on trailer and I have not noticed how far the transom sinks before float off occurs but must be less than if a roller trailer was used The external rubber flappers are in great shape. Motor is flushed after use in Salt water and this was done July 4 th. I backed it in a fresh water river near the house and ran it until warm. It ran fine. I have not been anchored up with the boat myself but have no idea what the previous owner did. I thought that running a motor after unloading for sometime would dry out a small amount of water injested thru the exhaust tips. (unless there is a continous source of water via a leak or exhaust issue) Sometime after the 4 th and before Labor day the valve became stuck while in the half open position causing the push rod to break at start up or soon there after. Labor day was the fourth time I've used the boat since buying.
AS Mr fixall stated, the stuck valve caused a vacuum and allowed water to invade the exhaust system. The heads go to the machine shop tomorrow morning for pressure check. Perhaps the cause of the valve sticking will be discovered. During the disasembly of the motor I did not find any gasket failures so I feel safe in saying the valve did not become stuck from a gasket leak. Thanks for all of the responses.:yes:

mrfixxall
09-16-2010, 11:47 PM
thanks for the measurement on the extensions for the risers. Right now planning on doing that as a precaution. My donzi is on a float on trailer and I have not noticed how far the transom sinks before float off occurs but must be less than if a roller trailer was used The external rubber flappers are in great shape. Motor is flushed after use in Salt water and this was done July 4 th. I backed it in a fresh water river near the house and ran it until warm. It ran fine. I have not been anchored up with the boat myself but have no idea what the previous owner did. I thought that running a motor after unloading for sometime would dry out a small amount of water injested thru the exhaust tips. (unless there is a continous source of water via a leak or exhaust issue) Sometime after the 4 th and before Labor day the valve became stuck while in the half open position causing the push rod to break at start up or soon there after. Labor day was the fourth time I've used the boat since buying.
AS Mr fixall stated, the stuck valve caused a vacuum and allowed water to invade the exhaust system. The heads go to the machine shop tomorrow morning for pressure check. Perhaps the cause of the valve sticking will be discovered. During the disasembly of the motor I did not find any gasket failures so I feel safe in saying the valve did not become stuck from a gasket leak. Thanks for all of the responses.:yes:

check out the piston rear good where the push rod broke..when the valve was stuck open it probably kissed the piston and that's what broke the push rod..next time when you get it running again,while flushing the engine and if the boat sits for a few months i would just fog the engine while your flushing it,,or spin off the fuel filter and dump some of the fuel out of it and add a few ounces of 2stroke oil to the center of the filter.. this will keep the valves and cylinders lubed up..

BTW here is a cheep source for the gaskets your going to need,this guy sells all the performance gaskets to mercruiser..

Performance Gaskets in German town WI 262-677-4690 bob is a really nice guy,i think i paid around 30 bucks each for marine ss head gaskets 12bucks pr for the exhaust and the intakes gaskets were like 13 bucks pr..he doesn't even ask for a credit card,he ships them and hopes you will send him a check..

poorboy
09-18-2010, 10:41 AM
Hey thanks Mr. Fixxall for the info for Bob in German town, Wi. Super prices! Great isea on the fogging oil! I'll make that a part of my routine when flushing the motor after each and every use. Sure beats all this trouble and a lot cheaper. I'll recheck the piston also to be certain there is no damage. The machine shop should have some info by mid week so I will be sure to post their findings.
I appreciate everyones help. :yes:

poorboy
09-19-2010, 04:08 PM
Rechecked piston, no damage at all. When I took the valve cover off the valve was not all the way open and the rocker arm was off the valve stem. The push rod was broke about 1 1/2" from the lifter and above that it was bent. When I looked at the face of the valve there was no damage to that either. Waiting on the reort from the machine shop now.

mrfixxall
09-19-2010, 04:51 PM
Rechecked piston, no damage at all. When I took the valve cover off the valve was not all the way open and the rocker arm was off the valve stem. The push rod was broke about 1 1/2" from the lifter and above that it was bent. When I looked at the face of the valve there was no damage to that either. Waiting on the reort from the machine shop now.

reason for saying check the valve is you said it was stuck open,the stem could be bent and thats why its stuck open..whyle its out i would check the rod bearing in that cylinder also,i have also seen where whed the valve comes in contact with the piston it cocks the piston in the cylinder and will crack the cylinder wall but that usually only happens to late model 5.7's..the valve did hit the piston,thats why the push rod broke and bent..

poorboy
09-20-2010, 10:35 PM
I understand what you are saying Mr fixxall and I greatly appreciate all the info. I can not find any damage to the piston at all. The valve was not stuck all the way open. If a piston struck the valve, it did not happen while the heads were on this engine. I am positive. From what I have determined, the 454 in this boat was reman. by merc. as vertified by their tag on the side of the block. Evidently, it was a short block and the heads from the original motor were reused or other heads were used. Casting number say used on 502 and some 454's on web site and just 502's in another book. The rocker arms are comp cams roller tip with screw in studs(adjustable) with the roller lifters, something I have not seen mercury use on the L29. The L29, Gen 6 should of had non adjustable rockers with the roller lifters from Gm. The motor is an 02. I also have a 01 L29 Gen 6 which has the non adjustable rockers and roller lifters. The boat is an 96. The previous owner said he saw the original papers and it listed the boat with a 454 mag. I believe 96 was the first yr of the L29 Gen 6 roller lifters and non adjust rockers. I have no idea what happen to the original motor. The valve stem may have been bent or tight in the valve guide when installed on the block and overlooked or not detected. I too thought the piston hit the valve when the compression test showed 0 on no.3 cyl. but the bore scope showed no damage and when the head was removed, still no piston damage at all and I rechecked it when you posted the info before. I was thinking that with the guide tight caused by bent stem or failure the push rod would be flexing each time it was called on to open the valve. When the valve finally stuck, most likely from setting, the motor cranked and the lifter pushed on the push rod which then bent and broke where it had been flexing all along due to the tight valve guide or bent stem. If not bent or failed guide then I would think water invasion may be the cause via crack or as you stated possible water leak around the guide or warped head but the gaskets did not suggest that. The valve stem was just about non movable in the guide. I did not remve the valve. The machine shop may have a clue tomorow and the cause can then be determined. Again, thank you for your and everyone else's help. I will post the shop findings.

poorboy
09-21-2010, 09:46 PM
Good report from the machine shop. There are no cracks or leaks in the heads when magnafluxed and pressure tested. None of the valves were bent. The reason for the valve being stuck is a rusty valve guide and stem. They further reported that all of the valve stems had rust on them. That points to the headers (manifold/ riser) being the cause. I water tested the manifolds (marine stainless) before with 40 lb water pressure and nothing was found. Will be using air pressure this time and submerge the manifolds in a water tank. Need to figure some way to check the risers with the air pressure also. If nothiong is found then I will extend the riser 3 or 4 inches as stated in an earlier post and use the fogging oil. Lots cheaper and far less work then this. Thanks much