Fire coming from exhaust manifold

[EMKFLYER]

I run my 2006 Sea Ray 185 Sport with the Mercruiser 3.0 in Salt Water. Engine serial number: OW604022. A couple days ago I saw a small water leak at the riser elbow gasket. I replaced the gasket and put the old riser back on the boat. I did see that the riser was pretty rusted and had small chunks of rust coming off on the inside of the riser. I put it all back together and it idled great. When I pushed the throttle up, the boat didn't have any power and started making loud popping. It sounded like an old WarWarII airplane. Now the boat quit and will not start. When I try to crank the engine, I can see fire shooting out of the side of the motor. (Hard to see exactly where, but it is under the area of the riser elbow....but not the elbow or elbow gasket). I assume it is the exhaust gasket.

I would really appreciate any help with this. Any ideas what has happened here? What damage has been done here? What can I do to prevent further damage? What parts should I order, besides a new riser elbow. Is there a company out there that is recommended for parts?

Thank you
Ed

 

[Don S]

Re: Fire coming from exhaust manifold

Pull the manifold, replace the gasket for sure, inspect the gasket surfaces of the head and the manifold. Replace as necessary.
Sounds like the manifold gasket burned through and may have taken out an intake port causing the problem.

 

[EMKFLYER]

Re: Fire coming from exhaust manifold

I just removed the manifold. The gasket is definitely burned through and blown out. After I removed it, I just taped the started to see if the engine would turn over. It sounds like it still will...however got what sounded like a backfire.

How will I know what to replace? I expected to see other damage or corrosion in the manifold, but overall it looks ok? Would a blown manifold gasket cause the motor to not run?

Thanks again
Ed

 

[Don S]

Re: Fire coming from exhaust manifold

Clean the gasket surface of the head and manifold and check for flatness. You don't want any areas where the gasket was burned up to be eroded away or the new gasket will never seal.

Would a blown manifold gasket cause the motor to not run?

It would if it got into an intake port. You would then have a huge vacuum leak and it would run lean and pop on that cylinder.

 

[EMKFLYER]

Re: Fire coming from exhaust manifold

Clean the gasket surface of the head and manifold and check for flatness. You don't want any areas where the gasket was burned up to be eroded away or the new gasket will never seal.



Thank you for your help again. I replaced the manifold gasket, checked the the riser elbow gasket, and carb gasket. All are in good shape. However, when I try to start the engine, I'm getting similar results. It still will not start and it sounds as though it is back-firing when it turns over. The battery is fully charged, but the starter realy sounds like it is laboring just to turn the motor over. What are your thoughts from here?

Thank you
Ed

 

[cr2k]

Re: Fire coming from exhaust manifold

Compression check.

 

[04fxdwgi]

Re: Fire coming from exhaust manifold

crossed plug wires?

 

[EMKFLYER]

Re: Fire coming from exhaust manifold

Compression check.

Ok. I did the compression check this morning. Cylinders 1,2, and 3 peaked at around 20 psi. Cylinder 4 was about 120 psi.
Is this a blown head gasket or a totally bad head? What next?

Thank you all for your help
Ed

 

[Don S]

Re: Fire coming from exhaust manifold

3 cylinders that low is not a bad head gasket. That usually happens between two cylinder or a single cylinder.

What's the background of this problem? Was there water in the engine? Have you done any valve adjustments?

Just to make sure, was the battery fully charged when you did the compression check? On all cylinders and the engine cranked over for all cylinders at the same speed? Normal speed, not slow because the battery is low.
Have a look at this service bulletin on doing a compression test properly.

View attachment 97-25 Compression Test.pdf

 

[EMKFLYER]

Re: Fire coming from exhaust manifold

What's the background of this problem? Was there water in the engine? Have you done any valve adjustments?

Just to make sure, was the battery fully charged when you did the compression check? On all cylinders and the engine cranked over for all cylinders at the same speed? Normal speed, not slow because the battery is low.
Have a look at this service bulletin on doing a compression test properly.

View attachment 188157

Thanks again for the quick reply.

The boat is 7 years old and only has 55 hours on it. The boat has always been here in Destin FL....so its alway been run in salt water. I recently got it so I wanted to tune it up. I rebuilt the carb, changed the plugs, and checked the timing. All was well and it was running really nice. Then I took it out Friday evening and the very first time I pushed the throttle up, it started popping and wanted to quit.

So then I found the manifold gasket blown. I repaired that yesterday.

I just read through the service bulliten and followed the directions but I'm still getting the same result.

I'm not sure what would cause this motor with so few hours to quit, blow the manifold gasket, now have low compression.

I would certainly appreciate any help from here.
Thank you
Ed

 

[Don S]

Re: Fire coming from exhaust manifold

With compression that low, I would have to bet on tuliped valves. (warped). Rings wouldn't be that low of a reading.

Follow the section on page 2 of the Serv. Bulletin titled Using Air to Test Engine’s Combustion Chamber in order to determine what the problem is before you pull the head. Nothing worse than pulling the head and everything looks normal.

 

[EMKFLYER]

Re: Fire coming from exhaust manifold

Ok will do. What would cause 3 cylinders to get bad valves and the manifold gasket to blow all?

Can the valves be replaced without pulling the head?

Thanks again
Ed

 

[Bondo]

Re: Fire coming from exhaust manifold

Ok will do. What would cause 3 cylinders to get bad valves and the manifold gasket to blow all?

Can the valves be replaced without pulling the head?

Thanks again
Ed

Nope...

 

[EMKFLYER]

Re: Fire coming from exhaust manifold

Ok. Pressure check complete. When I put air in the cylinders per the TSB it leaks out. I Can feel it leaking out the exhaust manifold gasket.....so that did not seal when I replaced the gasket this weekend. I also believe I can hear it blowing through the riser elbow on the other cylinder. Either way, the valves are not keeping the air in the cylinders.

What's next?

Thanks again. Ed

 

[EMKFLYER]

Re: Fire coming from exhaust manifold

Update: I decided to pull the head. 3 of the 4 cylinders had the gasket blown out. I took the head and exhaust manifold into the local machine shop. He said he would mill them and do a valve job for $300, and then get them back to me in a day or two.