manifold temp?

[jp6]

Have a 70's 351 mercruiser with heat exchanger. Starting it up in the yard the temp goes up to 140-150 degrees and the risers are cool to the touch. The exhaust manifolds both feel a liitle hot as I can only hold my hand on them for a few seconds. Was just wondering if this should be the case with the manifold temp? Thanks

 

[rodbolt]

Re: manifold temp?

hello<br /> I know this is going to sound funny but do you have a full closed cooling or a half?<br /> the difference is in full closed cooling the manifolds have anti-freeze circulating through them just like the block. this can be identified by the fact that there will be two 3/4 or 1" hoses plumbed to the manifold and one hose plumbed to the riser.<br /> look it over and let us know<br /> good luck and keep posting

 

[jp6]

Re: manifold temp?

There are two hoses plumbed to the manifolds(one from the heat exchanger and one from the therm/pump area) and one hose plumbed to the elbows(coming from the heat exchanger which t's off to each riser). I'm assuming this would be a full closed system? If so how warm should the manifolds get? How long should they last compared to the risers/elbows?<br /> Also I was told it was a rebuilt 351 mercruiser, but I cannot find any numbers where they should be, according to the manual(rear of cylinder head). How can I verify what engine I have if I can find no serial #'s or model #'s? The drive does have a # of 3648162. thanks

 

[rodbolt]

Re: manifold temp?

hello<br /> you have a full system. the manifolds will last years and years if the risers dont leak. if your in saltwater change the risers at 3 year intravels.<br /> the manifolds will run at engine temp. should be about 160 degrees F. the serial number should be on a plate at the stbd side of the block below the manifolds and just ahead of the bell housing.<br />unless the block was changed. then all bets are off.<br /> good luck and keep posting