mercruiser 7.4 water in oil

[gery w]

hi there ive recently noticed that my merc 7.4 is mixing water with its engine oil , ive checked the oil cooler for leaks by means of a pressure test but it turned out to be ok (wishful thinking). So i guess im now looking at head gaskets. Has anyone got any suggestions before i start chucking my hard earnt cash at it? thanks in advance

 

[omega2]

Not up on your engine but if it is fresh water cooled and there is a header tank then, run it up to temperature, so that the thermostat opens and with the cap off observe the water flowing in the header tank if you can see needle bubbles then suspect the head gasket is leaking.

 

[dingdongs]

get yourself a compression tester off ebay/remove plugs & pull centre lead from coil then see what results u get.should all be within 10% of each other.make sure too that no water is in any of the combustion chambers as this may be a sign of rotten manifolds.5 yrs for seawater use is average life expectancy.

 

[coliholic]

If you've got water in the oil, so a nice mayonnaise, then chances are it's a head gasket. But then you knew that already didn't you? So first off buy yourself a sniffer kit:

http://shop.ebay.co.uk/i.html?_nkw=combustion+leak&_armrs=1&_from=R40&_ipg=&_trksid=m37

Or maybe Halford's will stock it.

Whilst searching for that I came across this repair kit. If you have got a head gasket gone, might be worth spending £30 and giving it a go?

http://www.steelseal.co.uk/index.asp?function=DISPLAYPRODUCT&productid=1

But the real solution is a heads off job but that'll be the end of your boating this year.

 

[gery w]

thanks for the replies guys i dont think i can do a sniff test because it doesnt have a header tank due to being raw water cooled i also had the plugs out tonight to check for water and all looks ok so it looks like a heads off job and then take it from there thanks
gerry

 

[adey]

...it doesnt have a header tank due to being raw water cooled i also had the plugs out tonight to check for water and all looks ok so it looks like a heads off job..

Surely it's worth checking the manifolds and risers first? It doesn't take much water in the oil for it to make a gooey mess.

 

[carlton]

How old are the manifolds and risers?

If they've been on for more than five years they should be your first port of call.