mercruiser 454 too much steam in exhaust

[anglosax]

I have wellcraft 32 with 2 mercruiser 454 inboards. Engines are well maintained and run well but stb engine is steaming badly from the exhaust. There is plenty water flow out exhaust and under load at 1500rpm it is still only hand hot [60-70] deg after 20 mins or so. The coolant stays around 170 and nothing shows any sign of runnig hot or overheating. I have checked there is cooling water flow at the riser. where do I go next - possible air pocket in manifold? All ideas welcome. Thanks

 

[Black as]

Re: mercruiser 454 too much steam in exhaust

I would start with pulling the plugs on the stb engine and see what they look like.

 

[wire2]

Re: mercruiser 454 too much steam in exhaust

Logic says there must be a spot somewhere in that engine where water is being heated to past 212? F to make the steam.

A leaking head gasket might introduce water into a cylinder, then combustion will heat it to make steam. An easy check is look at all 8 spark plugs. If 1 is cleaner than the rest, it's a good indication. Since you now have the plugs out, try a compression test next.

 

[anglosax]

Re: mercruiser 454 too much steam in exhaust

Yes , you are confirming my worst thoughts - the steam gets more in relation to engine revs and is almost instantanious at start up even with a cold engine . Ok plugs out and comp test- will report

 

[anglosax]

Re: mercruiser 454 too much steam in exhaust

Hold on there guys , this is a FWC engine - no contact between combustion chamber and exhaust cooling water - only contact is at exhaust elbow- anymore thoughts?

 

[HT32BSX115]

Re: mercruiser 454 too much steam in exhaust

Howdy,


Have you removed the exhaust elbows and had a look at the riser gaskets? Also, after you shut down, does the engine act like the battery is low and have a hard time turning over?(which could be due to water leaking back thru the riser gasket into the exhaust manifold.)


It's possible that you have poor flow flow to one of the risers....(did you check both risers to see how hot they are? (I.E. can you put your hand on the riser and not get burned?) Get yourself a IR temp "gun" and check the riser temp to see if one is a LOT hotter than the other....(or they're hotter than the other engine)


Is this a SALT water engine? When were the risers removed, inspected and gaskets replaced last?





Cheers,


Rick