Does your engine temp fluctuate a lot?

[sewerrat]

As I cruise at low speeds at check out scenery, etc my temp gauge typically reads in the 210 range. Running on muffs at idle it stays at almost exactly 150. Cruising fast and pulling tube, etc it typically dips down in the 120 range.

Do I have some faulty thermostats, faulty gauge, faulty ??? or is this somewhat normal behavior for a boat?

 

[rbh]

Re: Does your engine temp fluctuate a lot?

because you said that if you are cruising at a low speed and it is running hotter than when your running at a higher rpm, it may just be time to put in a new impellor.
If the motors working harder so is the impellor, as per just idling. and the muffs with the garden hose turned on is just pushing the water in.
just my take on the issue
rob

 

[Thad]

Re: Does your engine temp fluctuate a lot?

I am on my third boat and by far runs the warmest at 170. It is a V-8. My V-6 ran a constant 140. When I get on plane in my current boat the temp drops to about 165. While playing hard, never has it been above 170.
Your engine will run cooler on muffs because there is no back pressure or load on the motor. Also at idle, due to not creating any friction heat because it is not being run hard.
As far as to the temp range you are saying, that is a really, really big jump and I would say something is not right. The "pro's" here will have more insight. I just was telling you what mine runs for temp.

 

[OMCboater]

Re: Does your engine temp fluctuate a lot?

1969 OMC 120 I/O runs at 145. Period. I was actually suspicious of the gauge because it is so consistent but early in the season one of the water lines blew off and the temp definitely did shoot up (at the same time as the engine compartment was filling with water) so I know it can go higher, it just never does. It does have a new impeller.

 

[oshkoshboating]

Re: Does your engine temp fluctuate a lot?

Similiar question: why oil pressure, when idling, will drop down to 40 which is almost in the yellow. But when I give it some gas, it shoots up to normal range. Is that okay?

 

[OMCboater]

Re: Does your engine temp fluctuate a lot?

Similiar question: why oil pressure, when idling, will drop down to 40 which is almost in the yellow. But when I give it some gas, it shoots up to normal range. Is that okay?

Yes, that is perfectly normal - all vehicle engines that I have worked on (and there are a lot of them) have that characteristic. almost in the yellow is fine, IN the yellow you might want to start checking some things out.

 

[oshkoshboating]

Re: Does your engine temp fluctuate a lot?

Danke!

 

[QC]

Re: Does your engine temp fluctuate a lot?

Guys . . .

1) This is the non-engine section so we need to move this thread to the right forum, but as far as I can tell we do not know what engine/drive/motor combo deal we have here.

2) Let's be careful about mixing in oil pressure and water temp issues in the same thread. That would be a hijack . . .

 

[rp23g7]

Re: Does your engine temp fluctuate a lot?

Mine usually stays at 190 at no wake speed and idle, it will go to 210 when i am crusing or pulling a tube, slow down and it goes right back down to 190.

 

[This_lil_fishy]

Re: Does your engine temp fluctuate a lot?

Similiar question: why oil pressure, when idling, will drop down to 40 which is almost in the yellow. But when I give it some gas, it shoots up to normal range. Is that okay?

This is normal, the reason you don't see it in yer car anymore is that a few manufacturers dumbed down the guages so that they don't fluctuate much under normal operating pressures. Something about people panicking on really hot days when the oil pressure gets quite low at idle thinking their engines are pooched and towing them to the dealer for warranty 'repair'.

Ian

 

[sewerrat]

Re: Does your engine temp fluctuate a lot?

It's a 1996 Johnson 115HP OB.
Sounds like impeller replacement is a good idea.

 

[redone4x4]

Re: Does your engine temp fluctuate a lot?

mine runs at 145-155 all the time, no matter what. and we do alot of tubing with a heavy load. I change the impeller at least every other season. Mine is a 87 5.0 OMC I/O.