1980 Mercruiser 5.7 with water in cylinder 7

I've been away for a while..... I just purchase a new to me boat, it's a project, probably long term. It's a 21' CC Scorpion with a 5.7 Mercruiser and I believe an Alpha one outdrive (I haven't checked the serial number tag yet). The PO has owned it for over 25 years. The 5.7 Mercrusier was replaced in 94. The boat was only in fresh water. Last year he had the exhaust manifold, risers, and water pump replaced. The engine and boat are in pristine condition.

This year after about 15 hours of run time on the new manifolds and risers the engine developed a problem where it started getting water in cylinder. He took it to a local mechanic who told him that he thought it was a head gasket problem. I don't know what if any test the mechanic did.

I'm looking for help on how to proceed with the trouble shooting of this issue. Before I go in and start taring things apart I would like to run some test to help pin point where the problem is. I was thinking of at least doing a compression test but I really don't know where to go from there. Any guidance would be greatly appreciated.

I'll bet a steak diner the exhaust manifold gaskets are leaking, allowing water into the cylinder via the exhaust port.

Jeff

.... and elcheapo non OEM exhaust elbows are prone to "water reversion" as well. I would not bet against Jeff, BTW, but to clarify... manifold to elbow gasket
.

I am doing some early investigating on my new to me boat. This boat is a 1980 but the motor was replaced in 1994. I'm wondering if I replace parts do I use part on the the 1980 or 1994. I looked on the valve cover and the there is a serial number on the valve cover but I would think if they replaced the engine in 94 it would have been replaced with a block that was a 94 era block and require 94 era parts. I no from looking that the motor is not electronic ignition it has points.

I went online and checked the manifolds and risers are different depending on the years as well. I don't know if it has anything to do with my problem of water in cylinder #7 but if the mechanic that worked on it last year possible used the wrong parts it's worth investigation.

Re: elbows...
see attached.


View attachment Modern wet exhaust engines are suffering damage from resonance reversion water ingestion with st.pdf

Thank you that was a very interesting article........

briang0 said:

I am doing some early investigating on my new to me boat. This boat is a 1980 but the motor was replaced in 1994. I'm wondering if I replace parts do I use part on the the 1980 or 1994. I looked on the valve cover and the there is a serial number on the valve cover but I would think if they replaced the engine in 94 it would have been replaced with a block that was a 94 era block and require 94 era parts. I no from looking that the motor is not electronic ignition it has points.

I went online and checked the manifolds and risers are different depending on the years as well. I don't know if it has anything to do with my problem of water in cylinder #7 but if the mechanic that worked on it last year possible used the wrong parts it's worth investigation.

Click to expand...

Take good photos of engine, Also, if center bolt valve covers count intake manifold bolts so we can assist in ID'ing the engine.

As far as water in # 7

Pull all plugs, Do a compression check and report results.

Typically when you have a reversion type issue (could be several different issues leading to water in cylinders) you would see multiple cylinders with water.
Only one cylinder may be bad head gasket (rotted an may be due to NON marine) or it just went bad?

Did engine over heat since engine was installed?

Here are the pictures of the engine.

Based on pictures

1986 or older TWO piece rear main seal engine. NON roller cam, . Log style exhaust manifolds most likely original to boat point ignition.
So I would say 1982-1986 350 GM

Note: if ENGINE BLOCK gaskets are needed such as head gaskets, They can be found at a local auto parts store FellPro Marine grade. I use NAPA
But of course OEM can be found below in link.

Link to this sites engine parts for this engine.

http://www.marineengine.com/parts/mercruiser-sterndrive-parts/260-gm-350-v8-19821986/6218462-thru-0b525981

I had some free time today and I was able to remove some of the panels that are around the motor. I'm getting it ready to do the compression tests. I noticed a few things that I would like to get some of the more experienced people out here opinions on.

The basic problem is that I'm getting water in cylinder number 7. I have not experienced the problem. The previous owner explained to me that was the problem. He said that last year he had new manifolds and risers put on and after approximately 15 hours of run time it started running rough and the marine mechanic he took it to said there was water in cylinder #7.

Today I took some close up pictures of the manifolds and risers. I also found another tag on the engine block with corroborates what the PO said that the engine was replaced in 1994. There is a metal tag on the left side of the block that has a model and serial number from a company call Sequel corp.

What I noticed was the exhaust manifolds that are on the Mercruiser 350 are 4 bolt manifolds but the gaskets that are used are 6 bolt gaskets. I can tell because I can see and feel the bolt hole on the last exhaust port on both sides and the exposed gasket. when using a 4 bolt manifold is there a 4 bolt gasket that should be used? The other thing I noticed was on the riser (see picture) there are 2 gaskets, is there suppose to be 2 gaskets? How do I know if I should be using a 6 bolt manifold or a 4 bolt manifold? Are there 6 bolt manifolds? It just seems weird that this problem started after the manifolds were changed.

Also while I was looking around the engine I noticed that the coil says should be used with an external resister but I don't see one. Wouldn't that cause the points to wear out faster?

Thanks in advance.

Brian

with a point ignition for mercruiser the external resister is within the wire harness. It is a special type of wire that generates Approx 2 ohms load.


The exhaust manifold bolt pattern is related to the type of manifold.

Center riser style (1983 and newer models) use 4 bolts.

The old log style exhaust manifolds (1982 and older) which you have, according to the parts breakdown use 8 bolts per side.

All small block gm V8 heads have two bolt holes per exhaust port, That equates to 8 threaded holes per side.

Center riser manifolds use only four bolts to attach to head.

Double check your manifolds to see how many holes there are and if any are unused (which would be incorrect) as all need to be used with bolts in each hole both sides.


Your picture of the double gasket between elbow and manifold

See link below to show what is supposed to be there. Only way to tell is to disassemble. It shows three parts in parts break down. a Stainless steel plate sandwiched between tow gaskets.

http://www.marineengine.com/parts/m...ru-6218461/exhaust-manifold-and-exhaust-elbow

Hi,

I know that the manifold has only 4 bolts holding it to the head 1 on each end and 2 in the middle. There are 4 nuts on top holding the riser on. When I look at the Barr manifolds on the link that you sent me they are 4 bolt also. I may be missing something. The gasket looks different than the one that looks like is being used on the ones installed on my engine.

B

The page said 8 required. I thought it meant per side and yes after looming at the parts it is only four.
So you are good.

Considering it`s only #7 , drain the manifold and elbow and pull the elbow for inspection

A very sweet vintage boat. If you have the budget, then I would pop for all new exhaust. I'd go to a center dump style or even a performance thru-transom style. The boat deserves it and you will recoup your money if you decide to sell. A potential buyer wants to see a nice engine compartment with new parts, not that rusty lump you got going on there,
If it were me, the engine would be coming out so that I could get a look at the bilge, the engine mounts, the stringers and the transom. It alll would get a good cleanup and a fresh coat of bilge grey. I would replace the bilge pump and blower.
While Chris Craft made tons of these, they still hold their value. Worth throwing some money into.

I pulled the exhaust manifold and riser off the engine today. I couldn't see any issues with the gaskets on either the manifold or the riser. I took a few pictures.

What I did notice as I was attempting to do a compression test was that even after the manifold was removed I was still getting water coming out of the exhaust port on cylinder number 7 and I also noticed a little water coming out of cylinder number 3. Since the manifold and riser were off I don't think the water was coming from the exhaust manifolds.

Does this mean I'm looking at a head problem? My compression gauge was not reading reliably so I don't trust the numbers I was getting. When I get a new gauge I'll run the test again

I also would like to know if it's possible to winterize the engine without running it? I was thinking I could drain the manifolds and the block which I already have done. Then pull the thermostat and pour a couple of gallons of pink antifreeze down in there. Then I'll drain the block again and

View attachment 25034View attachment 25035

HI, I let this set all winter I did my best attempt to winterize it last fall. I poured 2 gallons of pink antifreeze down the thermostat hole after I pull the thermostat out. After that I drained the block down and while the plugs were out I sprayed fogging oil in liberally into each plug hole and also down the carburetor. Although I haven't unwrapped the boat yet I'm trying to get my plan of attack for when I do hopefully in about 3 weeks.

I am planning on:

The first thing I want to do is spin the engine over and see if any water comes out of Cylinder 7
Redo my compression tests with a working compression gauge.
ordering new exhaust, and riser gaskets
Pressure testing the exhaust manifolds

If anyone has any other ideas on figure out why water was showing up in cylinder 7 I would love to hear it.

Thanks,
Brian

Hi,

I unwrapped my boat this weekend. I finally got to use my new compression tester to get some number of the compression of the cylinders.

They are:

Left Bank
1 135 psi Cold I let it set for 15 minutes and it held the pressure.
3 135 psi Cold Held pressure for 15 minutes
5 140 psi Cold Held pressure for 15 minutes
7 120 psi Cold pressure dropped 5 psi then held This was the cylinder with water problems from the original post.

Right bank

2 150 psi Cold Held for 15 minutes
4 125 psi Cold Held for 15 minutes
6 135 psi Cold Held for 15 minutes
8 115 psi Cold Held for 15 minutes

The engine has 452 hours on it. It was rebuilt by a company name Seguel. They are not in business anymore. With the these cold compression readings I'm wondering if I should bother going any further with this block. I have not found any exhaust manifold gasket issues. The manifolds and risers have about 15 hours on them. The original issue was the engine was getting water in cylinder 7. I witnessed it after I purchased the boat I pulled the manifold and plugs and when I spun the engine over I noticed water coming out of the cylinder 7 plug hole.

Am I looking at a short block? the engine appears to be in good shape. It has been in fresh water since the engine was installed. I do not have the resources to rebuild it. I can replace head gaskets and send the heads out but if the compression readings are such that it would be a waste of time I don't want to.

Any thoughts?

Thanks,

Brian

The saga continues. Today I went out and ran a leak test on the port head which is the side that was having the water issue. My test results on all the cylinders were normal the gauge stayed in the green. I also pressured tested the exhaust manifold on my bench and found that there was not leaks in that.

So now the compression test although not optimum still were not terrible. The leak test passed. The pressure test passed.

I decided to put the manifold and riser back on and all new gaskets it was getting late and I'm not as strong as I use to be so hopefully tomorrow I will try starting it up and see what happens.

If I'm still getting water in Cylinder # 7 I'm not sure where I'll look next.

I started up the engine this afternoon. It took a little work and I had to clean up the the points after that it started up. I let it run for about 10 or 15 minutes so that the engine go good and warm. I can't run it much above idle because my well would have trouble keeping up with the demand plus I have to run about 75 feet of garden hose out to the boat. The engine ran well did not skip or miss. I shut the water off right after I shut the engine down. Next thing I'm going to pull the number 7 plug and spin the engine over and see if any water comes out. That probably won't be for a couple of days.
It was nice to see the motor running but all I did was replace the riser gaskets and exhaust gasket. I'm usually not that lucky.

Does motor hydro lock? Sometimes? Is it a possibility that exhaust baffles are gone?

If riser gasket, most of time , I'll see a rust trail .

The motor is a 1980 - 1984 Mercrusier 350 I/O when I had the port riser off I looked down and I did not see any flapper. I didn't see any "place" for one. I only removed the port side I did not touch the starboard side. Where are the flapper/baffles located.

Mickey N.C. The P.O. said that the motor started running rough about 15 hours after he had the exhaust manifolds and risers replaced. He brought the boat to his mechanic and the mechanic said there was water in cylinder 7. When I got the boat and pulled the plugs and spun the engine over I notice a small amount of water more like a mist of water coming out of cylinder 7. I had already pulled the exhaust manifold and riser on that side I didn't see any rust trail on the riser gasket the seal looked good. It was late in the fall so I fogged the cylinders the best I could without running the engine and winterized it by pouring pink into the block through the thermostat housing and water pump. I then drained it out. Flash forward to spring and compression, and leak down tests and here I am.

I’d try to get it up and running and run it take a hot compression test and see if any water comes out of that cyl, if not I’d use it but keep checking for water in the oil. Cold compression tests are not as accurate as a hot compression test with the throttle valve wide open.

When u had exhaust manifold off , did u look at exhaust valve stem on #7 ? Look for rust high on stem. That can sometimes be a clue, it's on exhaust side.

And also I said baffles , I meant flapper lower in exhaust tubes to keep back flush of water.

I let the engine sit for about 5 days and I pull the number 7 cylinder plug and spun the engine over and I would say about an ounce of water shot out. I do know where the water is coming from. All my test say the head gasket and valve train is in good working order. It's looking more and more like there is either a crack in the block or the head. The water has to be coming from some where. If the intake manifold or gasket was bad could it come from there? Or am I just grasping at straws now and should just start ripping the top off this motor. I'm thinking this is turning into a project I don't want to get involved in I was not looking to swap the engine.....

A rotted area on the intake with water flow is restricted to the coolant crossover in the front right under the thermostat housing. So that would put water in the cam valley right into the oil but not in a cylinder. Water in a cyl will most likely come from a manifold/elbow, a bad head gasket or cracked block. Cracked heads are common from past overheats but block cracks from overheats are not likely, they are more commonly seen from improper winterizing. So if you’re sure it’s not the manifolds you’ll be pulling the intake & heads. Take the heads to a machine shop to check for cracks. Make sure the sealing surfaces of the intake are flat & level.

Another test you can do before taking it all apart: pressurize the cooling passages with air to about 15 psi after draining water & see if it holds pressure
also you can put the boat in the water, replace the manifold feed hoses with clear hose. Run it till the engine warms up and the stat opens. If you see bubbles in the cooling water then that means combustion gas is leaking into the cooling water which suggests blown HGs and/or cracked heads.