Dirthead

I may be biased, but I believe this is the ultimate boat horror story! This problem started late last summer after I purchased a 1995 272 Islander Baja with a carbureted Generation V Merc 454, SR number OF413462, with a Bravo 1 drive. The first 3 times I have had it on the water (fresh water only boat) it has overheated. The first time I took it out it overheated, 230 degrees F, right away. As soon as I heard the warning buzzer go off, I shut the engine down and then heard every cylinder fill up with water (this boat does NOT have through the haul exhaust). The engine was very hot (boiling water when splashed on the block, but there was NO water in the engine compartment and NO water in the engine oil). I towed it to the marina and they rebuilt the fresh water pump (the veins on the old pump were all intact and looked fairly good) and replaced the bellows boot. Took the boat out for the second time and the same time happened, but this time it would get hot only if you ran it at half to full throttle. If you went back to idle or lower throttle, the temp would go back down. I took it back to the same marina and asked them to replace the recurculation water pump. They did not and said that would not be the problem. They went through it again and found no problems. They checked every hose looking for restrictions and found none. They did replace the thermostat. The next time I took the boat out we ran it for 3 hours, at full and half throttle, and had no problems then all at once, it got hot again. I turned the engine off and heard the cylinders gurgling and belching and filling up with water again (again no water in the engine compartment and no water in the oil). I pulled it to my business( I own a trucking company and have our own diesel repair shop). We did a compression test and showed good compression on each cylinder, thus somewhat eliminating the possibility of a blown head gasket. Again with no answers, I took it to a different marina. They removed the circulating water pump and said it looked good. They also looked for restrictions in all the normal places and found nothing. They were stumped and did not know what to try next. I picked it up from that marina and took the boat to yet another marina and had them look at it. I had them replace the exhaust flappers with a new style (although the old ones appeared to be just fine). They also did a leak down test and said that it leaked compression in between three cylinders. I picked the boat up, brought it back to our shop, and removed the engine. I pulled the heads, the gaskets looked just fine, with no signs of being blown. I had the heads magnifluxed and they tested out just fine. I pulled the frost plugs and thought that the block might be full of sand however found no sand inside. Needless to say, I am at a total loss as are the 3 different marinas that looked at the boat.

Later this winter I believe I found the problem. There is a water hose that runs up over the drive unit, in through the haul, and into the engine. This line supplies the boat with water and it had been pinched pretty severely. I replace this hose and all of the overheating issues went away when I had the boat on the water this spring.

I went ahead and completely rebuilt the motor this past winter. I put Elderbrock RPM performer heads, forged SRP flat top pistons with a compression around 9:2 to 1, a Elderbrock air gap intake, a Comp Cam Hydraulic roller cam that is 224 duration at 50 and has lobe separation of 112. In addition I installed a new timing gear and chain, roller rockers, new pushrods, new head bolts, a water bypass kit (this replaces the circulation pump), 142 degree thermostat. Also I installed a Lightening header system which has 4 “ of riser and the Lightning’s switchable exhaust diverters which exhaust out a the factory Y pipe or through a pair of tips that have internal flappers to keep the lake water from reentering the engine.

The first time I took the boat out for it’s initial break in I could only get the engine temperature to 120 degrees with a 142 degree thermostat. I replaced the 142 thermostat with a 160 and the engine immediately shot to 200 degrees while at idle. I shut it off and replaced it with a different 160 thermostat and again it shot to 200 degrees. I put the 142 thermostat back in and the temp has stayed at 140 degrees of less ever since.

Here is my problem. This motor only has 4 hours on it and I keep getting water in my oil. After about 4 weeks of troubleshooting I have narrowed it down. I have done leak down tests and they were fine. I have done compression tests and they were fine. I removed the thermostat and put a plate over the thermostat opening on the intake manifold and placed a fitting on it so I could put a garden hose on the cooling side and held the water at about 60 PSI for 12 hours and still had no water in the oil. I removed the oil cooler and tested it for leaks and found none. IF I did my compression and leak down tests properly, I should not have a head gasket gone bad from the one occasion of the temp going to 200 degrees.

I continued to eliminate sources for the problem. I put the boat on the hose and have ran the boat 4 times at 30 minutes, with RPM's between 400- 1800, and with the water exiting through the Y pipe and never get water in the oil. Then I switch the exhaust and have the exhaust exit through the haul tips and every time I get water in the oil after 10- 20 minutes. I have done this 5 times and every time I get water in the oil.

This has me baffled. I would think that when the exhaust is open out the rear tips that there would be less restrictions for the water to be sucked back into the engine oil. When the exhaust is switched and exiting through the prop, I would think that there is more restriction as the exhaust hits the diverter and has to travel down the Y pipe. At 400- 1000 RPM’s I can hear the internal flappers bouncing inside the tips. They really make a lot of noise. Initially I thought that the exhaust water might be hitting the flappers at the point when they have fallen shut and at that point was being sucked back into the engine. Therefore I wedged the flappers open and retested. At the end of another 20 minute test again I had water in the oil.

At this point one would think that I have found my problem. I contacted the exhaust manufacturer. He instructed me to cut the water that was going to each header in half and to dump the other half out the haul. He also sent a pair of Shotgun exhaust tips from drewmarine.com. These tips are to help with the reversion issue and he felt this combination would solve the problems.

I installed the tips and reduced the water traveling through the headers and took the boat to the lake. I took the boat to Lake Darling on a Friday night and left it on the trailer but backed it into the water. I ran it for 30 minutes with the RPM’s going from 600- 1800 and with the exhaust going out the rear and checked the oil and all was good. Again I backed it in and ran it for 25 minutes, this time with the exhaust going through the prop and checked the oil and it too was fine.

On Saturday I took the boat to Lake Rathburn. I unloaded the boat and ran it for less than 5 minutes with the RPM’s between 500- 4000. At the 4000 RPM range I heard a loud ticking noise (The engine has always had a tick noise at idle. We adjusted the rockers once and the tick still was there so we were assuming that the tick was an exhaust leak). I checked the oil and again it was milky in color. I had put 7 ˝ quarts of oil in the engine. While the boat was in the water it had the exhaust going out the rear transom and not through the prop.

One thought would be if the cam is NOT the 224 at 50 cam that I ordered. The cam card says it is, but there is a remote possibility of the wrong cam being sent. I called the Comp Cam rep and he said the next step is to degree the cam and the check the intake centerline in the motor. We lined the dots on the timing gear and cam up when we installed the cam. Another possibility would be if the block was cracked from the high temp problems for last summer. However I would have though that is the block was cracked it would have shown up when they bored the block 30 over when I rebuilt it this summer.

I am completely baffled. I was getting water in the oil with the engine running on the muffs and the exhaust going out the rear but not when the exhaust was going through the prop. However when I but the boat on the water while it was on the trailer I did not get water in the oil while the exhaust was going out the prop OR the rear. I have gotten the water in the oil with it being at a low RPM test as well as a operating at a higher RPM range. There in no trend to follow which is making this incredibly difficult to diagnose. The water in the oil problem does not seem to be heat related because the engine never gets that hot. The water in the oil problem does not seam to be RPM related because it has happened at low RPM’s some times and other times it does not. They do not happen with the exhaust at one position or another. I have gotten water in the oil while it was running on the muffs and while running on the lake.

Not only has this engine bleed me to death financially ( I have spent well over $10,000 in parts and have not even begun to count the labor bill), but also the time away from my family is taking its toll. I have worked on this engine at least 3 nights a week and every Saturday and Sunday for over 4 months now. I need to find the problem.

What should I do and can anyone explain to me why this is happening. I understand that reversion is caused mainly by where the water is being inducted in the exhaust and by the cam that you have. But under my tests, neither has changed. Under each test, my cam is the same and the water is inducted in the exhaust the same, just as it leaves the headers and before the diverter valve.

Please help!!!!! Any ideas would be very welcome. Please feel free to email me at [email protected]

jackhammer

I had an intake manifold/gasket leak water into the engine.

Lofty

Intake manifold! Did you check that the gaskets are correct when you installed? It's also very common for people to use WAY too much silicone on the gaskets when they're installed.

The Lightning headers don't reintroduce water back into the exhaust intill way back so unless you have a real lumpy cam this is not the problem. Anyhow, that's an easy check. Idle the motor for 10-15 mins then pull one of the headers. If there is any water at the head you have reversion, otherwise you're ok.

Good luck,
Fionn

birdog

Checked your water pressure ?...Crossovers can cause very high pres.

Vinny P

I am fighting a similiar problem. Over the winter I built a fairly stout naturally aspirated 540. On my first test run, I encountered reversion. I had a little water in the oil and salt deposits on a couple of plugs. The idle was terrible, I would develope a miss due to plugs fouling with water. At the time, I had a set of Gil WetOffshore manifolds and risers. They dumped the water directly in front of my thru-hull tips. I removed the risers and found alot of water in both manifolds. So much that I originally thought that my Gil manifolds may have rotted or cracked. I pressure checked them and found them to be good. I just got a set of CMI elbow top headers. I was told that they would end my reversion problems. Well, they didn't. It is alot better, but it still there. The engine does not miss anymore, the plugs and oil are both clean. I found the problem when I spotted a drop of water coming from the cool collar joint on the headers. So, I removed the gasket and left the clamp slightly loose to help any reverted water leak at the joint, rather than fill the motor up. And leak it does, I have a mess after a days running around.

I don't have a radical cam.

all measurements are @ .050" lift

intake: .578 lift...238* duration
exhaust .608 lift...248* duration
114* lobe seperation
ivo 5* btdc....ivc 53* bbdc
eco 58* abdc....evc 10* atdc

Not alot of overlap, but apparently enough to cause a problem. My next step is to go full dry pipes. That will certainly fix all my problems.

I realize that your problem is more involved than what I just described. But, my point in sharing this is that I don't think that there is any definitive answer the mystery of reversion. I talked to all the cam companies before deciding on this grind. They all said I would not have problems with reversion. The exhaust companies would not give me their opinion at all. They said, if I want to be sure, do dry pipes. So, tomorrow I will be calling TrickMarine for dry tailpipes.

JimV

iTrader: (1)

How much drop is there from the manifolds to the transom? Is it possible that when you were running at the ramp that the bow was higher than when the boat is off the trailer? Just a thought

articfriends

iTrader: (1)

What cyl heads are you running?

Dirthead

Articfriends: I am running Alum Elderbrock RPM performer heads.

JimV: the trailer was compleatly submerged and th boat was free floating while it was on the trailer.

Birddog: I have not checked my water pressure. What are you sugesting about the crossover?

Jackhammer and Lofty: If it was intake gasket, I would have thought that it would have shown up when I did the leak down lest or when I pressurized the cooling system. What do you think??

Lofty

An intake leak sure won't show up on a leak down. Pressure testing the cooling system doesn't always show these leaks either. most of the time it takes some heat to get the castings to move a bit before the leak shows up. Also, just a little corrosion on your castings at the gasket face will cause all kinds of trouble once the motor warms up. If you don't have a solid sealing face the gasket will leak.

Vinny P

Articfriends,

I am running AFR 315 cnc heads. I talked to Jeff from CMI today. He suggested something that I just didn't think of. He said to remove the rubber flaps on my tips. They may be causing just enough restriction to cause my problem.