AQ145a Motor

"what sort of problems do you

"what sort of problems do you encouner when the exhast manifold is suspect of corrosion.i have repaired the no.4 port with a filler (lead) seems to work very,very good after i had tried a number of aluminium filler products.i suspect that there is water going into the no 4 port because i started it up on one of our outings and heard a noise like the valve had had a bit if rust in it and sounded like a valve stem dry and rubbing in the head.this only lasted for about 1 min (max) and was quiet after that.trying to get the most out of this fishing period before i remove the exhaust manifold to see how corroded it is.i suspect the manifold is not in a good condition and trying to avoid big codts.will running it in this condition have bad results for a the next month or so,or will it be the same.i donrt have any problems with the motor at the moment it run very good.i will inspect the manifold when i take it of but from experience from youall i would like an opion if these manifolds are successfully welded after corrosion sets in or do you think that they are a complete waste of time rebuilding.i also will have to face the situation abount the head in regards to the ports 3/4 to see if they are servisable or not.comments please"

"If You successfully manage to

"If You successfully manage to weld a 20+ year cast iron exhaust manifold that has been running in salt water (?), I will nominate You for the Nobel Prize! It sounds that Your warning bells have allready been ringing in cyl4, and he ringing will probably be more frequent until total silence!"

"Regarding the manifold, when

"Regarding the manifold, when they rot, they rot and they cannot be repaired. I would scrap it and get an afetermarket from Sierra.

http://www.marineengine.com/parts/part_details.php?pnum=SIE18-1930-1&returntopag e=80240783.htm

Regarding the head, you can remove it from the engine and send it to a shop where they can build-up the corroded ports. However, I suggest it may be cheaper to obtain a used automotive head from an autowrecker and install it with your current camshaft (an automotive camshaft will not perform well in a marine engine)."

do you know what part of the m

do you know what part of the manifold rots to cause water to destroy the head i would like to understand the way it works.

"Mainly the rear end where the

"Mainly the rear end where the temp is the highest, walls are the thinnest and the water mixes with the exhaust and the distance to the no4 cylinder exhaust port is the shortest. The original Volvo manifold had a dividing wall to prevent some ingress of water to the exhaust port, earlier Sierra manifold did not have this wall, I think they got it later, but not sure.
However cast aluminum of the quality used in the head is not intended for the salt water environment it is exposed to, but as a car engine part. This is noticable on most of the parts on this engine like the aluminum covers in front, lower timing belt gear etc. This is a car engine, dimensioned as a car engine, but with a water cooled manifold added."

thank you for for the explanat

thank you for for the explanation .I like to know the insides & out of problems