Water Temp

[351 OMC]

I have a 1994 351 omc, efi, I/O with a Cobra SX outdrive. The impellor is mounted on the bottom right side of the engine trust me on this, it's NOT in the outdrive). I bought the boat 5 years ago and have never replaced the impellor until last year (saltwater use). When I got the boat back from the shop I noticed there was no fan belt on the impellor pully. The water temp always ran about 150 to 160. Book says the thermostate should open at 160 and it did. I put a belt on and the water temp dropped to 125 to 130 and I ran it for about 40 hours this way. I asked the guy I bought the boat from if he ever replaced an impellor fan belt and he said it never had one. The boat shop never questioned the fact it didn't have one and didn't put one on.

Can this temp be to cool for this engine? Is there supposed to be a fan belt? It ran for12 years and 700 hours without one. Should I take it off so the temp will go back to 150-160? Could this be something that would make the engine surge from 500 to 800 at idle? Thanks

 

[Don S]

Re: Water Temp

Without the raw water pump belt on, I can't even tell you why it cooled, or how it's even possible.

Personally, I don't even believe it did.

 

[Reel Poor]

Re: Water Temp

Are you saying the shop put a new impellor in and returned the boat to you without a belt on the raw water pump because it didn't have one on it when it went in for repair ?

I would put the belt on and replace the t-stat.

 

[bruceb58]

Re: Water Temp

It had to have had a belt on it...impossible for it to cool otherwise. You would have also burnt up your exhaust hoses.

 

[Bondo]

Re: Water Temp

Ayuh,......... You're Not making Any sense.....
Waterpumps Don't Pump when Not powered......

 

[351 OMC]

Re: Water Temp

The engine mounted water pump was working. It was the impellor mounted on the lower right side that didn't have a belt on it. I know it's hard to believe but true. The engine mounted pump was obviously strong enough to cool the engine sufficiently and the hoses were fine on inspection. I just put brand new hoses on but the old ones coming off were still plyable and not cracking.

My question is, for this engine, should the temp be around 120 or around 160 and if it is cooler than it should be does that effect the EFI system at an idle. The book says the thermostat (which I just changed) should open at 160 but right now the temp only goes to 130 max.

 

[Bondo]

Re: Water Temp

Being Cold will cause it to run Rich............ I'd replace it.....