84 searay/260hp mercruiser

[blh1972]

The last time I had this boat out it ran fine, but when I got back to the dock it idled a little rough. pulled the arrestor off the carb and noticed it steaming from the valve cover vent tubes. so what do you guys think head gasket? doesnt show any water in the oil yet?

 

[Reel Poor]

Re: 84 searay/260hp mercruiser

When was the last time it had a tune up? Plugs, wires, cap, rotor, fuel filters, carb adjustment, and timing (base and advance) checked.

 

[blh1972]

Re: 84 searay/260hp mercruiser

It was tuned up this spring. The thing that bothers me is that it is puffing steam out the valve covers.

 

[capecodder116]

Re: 84 searay/260hp mercruiser

Have you pulled spark plugs and check their condition??

 

[Haut Medoc]

Re: 84 searay/260hp mercruiser

Have you pulled spark plugs and check their condition??

Have you pulled your spark plugs & checked for water in your cylinders?
If your plugs look steamed clean that would be a clue.....
I'd be more likely to think that an exhaust manifold/ riser or the joint between them is going bad......​

 

[blh1972]

Re: 84 searay/260hp mercruiser

I will check the plugs today.
How do I check the manifolds and risers?

 

[Haut Medoc]

Re: 84 searay/260hp mercruiser

Unbolt the riser & check the mating surfaces for signs of leakage.....
Get a flash light & look down into the exhaust port of the manifold.....
You should not see rust......
Run the engine before you pull the plugs, this will allow you to see if there is a wtaer problem before it has time to seep past the rings...
How old is the exhaust system?......​

 

[blh1972]

Re: 84 searay/260hp mercruiser

According to the block casting number it is 96' or newer engine, don't know if the exhaust was changed then also or not?

 

[Haut Medoc]

Re: 84 searay/260hp mercruiser

All ya can do is pull it apart & look.....
Ten years is old for a manifold in fresh water use.....
In salt water, I would say it is well beyond it's time.....​

 

[blh1972]

Re: 84 searay/260hp mercruiser

OK, got manifolds off and checked them on a garden hose they check out OK lots of water flow and no leaks into exhaust passages. I have had a new long block shipped in marine block, with vortec heads, mercruiser performance grind camshaft, marine gaskets, all new marine accessories, etc, etc, $$$$
I am in the process of switching the engines out, I guess I will try to re-use the manifolds they don't look very old? What do guys think?