Mercruiser Temp Question???

paultallett

paultallett

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Odd question but it's puzzling me!!

Since I've owned my boat fitted with a Mercruiser Mag 350 MPI the port manifold has always been warmer to the touch than the starboard one.....I'm not talking like its glowing red, but after running up to temperature (then shutting down I must add..) the starboard one is hot and the port one a bit hotter.

The engine has always run as sweet as a nut and the temperature gauge is rock steady where it should be.....So is the temp differance normal or should I be investigating a blokage somewhere?

As the saying goes 'if aint broke don't fix it' and thats what I've heeded so far, but I'm now curious!!

I wait to be put right!!!! /forums/images/graemlins/smile.gif
 
One side of my Mercruiser (5.0LX/Alpha1) always runs slightly hotter than the other, too.

I've assumed it's because there's a slight difference between water flows into the exhaust each side, maybe because there is a bit more internal corrosion one side than the other.

There is a flow balancer in front of the thermostat housing on mine (direct seawater cooled, closed circuit system would obviously be different). If yours is the same, it may be worth disconnecting the hoses leading to the exhausts to check that neither of the spring loaded balls is stuck.

One of the routine checks I do on the first start of the day is to feel the temperature of the exhaust outlet elbows a few seconds after starting. I know how quickly they warm up when all is well, and if they are getting too hot too quickly that would indicate no cooling water flow or one side completely blocked, either of which would warrant investigation before casting off.

I am also a great believer in "If it ain't broke, don't fix it", so I have not investigated further.

Hope this helps.
 
Thanks for your replies Rob & Excalibur. I'd kind of thought along similar lines as both of you. In fact Excalibur you sound as bad (anal) as me for knowing all the various parts operating temperatures!!!

It's only the manifolds that feel slightly different, the risers & elbows are almost the same...and surprisingly cool..., so I've put it down to a bit of corrosion or blockage in the said manifold, but wondered if it was a quirk of the Mercruiser engine before I start to take a spanner to anything!! /forums/images/graemlins/smile.gif

Do you think it can be safely left until the boat is ashore at the end of the year (asuming no running problems) and then I can give the whole system a good flush out and clean during the down time?

Regards Paul.
 
[ QUOTE ]

Do you think it can be safely left until the boat is ashore at the end of the year (asuming no running problems)

[/ QUOTE ]

Almost certainly. As we've already said, it ain't broke so not much point in trying to fix it IMHO. I think Ballistix may be on the right track in pointing out the cooling water probably goes to one side first so that will always be cooled a bit more. Hadn't considered that before. /forums/images/graemlins/smile.gif

I've always been a bit paranoid about losing the cooling water flow as that can really spoil your day. With outboards you can always see the tell tale peeing out, but no way of telling with an inboard until it starts to overheat, and I really want to know about it a bit before that. /forums/images/graemlins/frown.gif
 
Thanks guys for your words of wisdom..... /forums/images/graemlins/smile.gif

I think its a case of keep an eye on things (business as usual then!!) and if I'm really bored over the winter I might just pop the riser off to see if anything is inside.

Regards Paul /forums/images/graemlins/smirk.gif
 
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