5L Volvo Penta Running Rich

"I have a 5.0L Gi with a SX ou

"I have a 5.0L Gi with a SX outdrive in a 1999 Chaparrel 240 Signature. When the engine is cold acceleration is fine. After running a few minutes and the engine gets up to temp, the engine lacks acceleration and acts like it is gettin too much gas. I have replaced the plugs, wires, rotor, distrib cap and checked timing but the problem still exists. The plugs are black and I get occasional white smoke from the exhaust. Any idea what the problem is? The motor only has 270Hrs."

"White smoke is usually steam

"White smoke is usually steam caused by water reaching the cylinders. Possible causes could be one of your exhaust manifolds being perforated, or one of the heads is cracked, or a head gasket is defective ."

I'm with El on this one.

I'm with El on this one. Get a compression test done before running it any more.

Jeff

"Ok, after 2 people suggesting

"Ok, after 2 people suggesting a compression test, I took my guage and ran the test. All Cylinders except #4 had 170 to 180 lbs of compression. #4 had no compression. Took the boat out of the water so I could tear it down and determine the problem. I will let you know what I find."

My guess is You will find a &#

My guess is You will find a 'mushroom' valve.

One thing I would check before

One thing I would check before starting a major surgery is the valve adjustment in #4 cylinder. The problem could be something as simple as a defective lifter or an improperly adjusted rocker.

I got the head off and the #4

I got the head off and the #4 exhaust valve is badly burnt. Time to take the head to the machine shop.

"If the exhaust (small&#41

"If the exhaust (small) valve is burned and no signs of water from the manifold, I suggest You change the lifter befor assembling the engine."

I made a mistake in my previou

I made a mistake in my previous post. It was the intake valve.

'Mushroom'?

'Mushroom'?

I am not sure what you mean by

I am not sure what you mean by mushroom. The Valve is blistered and material is missing. The Valve stem sits atleast 1/8" higher than the other valves. You can see the edges of the Valve Seat next to the valve.

"Morten: You gotta be psychic

"Morten: You gotta be psychic!

A mushroomed valve is one that tries to slip up into the head on its own. That's about what you have. You need to find the reason why this happened (lean carb, not getting gas at speed, etc.) or it will happen again.

Finally--you won't like this part--ALL of the valves need to be replaced or you will 'drop a valve' and destroy the motor. The condition of excessive heat that wrecked that valve also removed the hardness of every exhaust valve as well.

Jeff"

"It may not be as bad.
'M

"It may not be as bad.
'Mushroms' normally occurs after launcing the boat in spring time or after prolonged storage.
'Bad' fuel may be one thing , causes lean burning. Corrosion on valve seats is another and the most common. In theese cases there is normally a pop or two in the carb/throtle body and a rpm loss of a couple of hundreds. If fixed asap,no big deal, just change the dammaged valve.
Third common reason is a stuck lifter that does not properly close the valve. The reason for this may vary, but oil quality and type may be a factor. Most cases I have encountered with this reason has been when customer has not changed oil before storage.
One good tip when taking a V6/8 out of storage is to let the engine run some 15 min under light load to let the valves seat properly and if stored with full tank, do not push to hard until fresh fuel has been filled. 'Old' fuel burn slower and encreases the risk. For injected engines, always store with a conservation fuel mix in the system. 1 quart Fogging oil and fuel stabilizer (2+4) in a 4 Gal outboard tank is almost a must. The worst for an injected engine is to run it dry!
Had it been an exhaust valve I might have agreed to Fastjeff: change of all might be needed, but intake valves, it just happends from time to time! Not the first case on this board!"

I have owned the boat for a li

I have owned the boat for a little over a year. When I bought the boat it had been sitting in a marina for about 6 months unused. The marina was in salt water. The owner had bought a bigger boat and did not use this one. I have not had the boat in storage since I bought it. It has been in a fresh water marina year round. The engine only has about 270 hours. The engine is a GM based 305 with throttle body injection. The problem might be some corrosion on the intake from sitting for all that time in salt water. all the other valves look great.