engine water pump hose to hot

[eric b]

hi this is my first time so be gentle. i have a 1989 4.3 mercruiser and a mercruiser out drive. i ran my boat today in the river still on the trailer to check to cooling system and the gage never went hot but the big hose from the engine water pump to the t-stat housing got vary hot all most burnt my hand is this normal or do i have a problem. it has a new out drive rubber pump,engine water pump,t-stat. (this only has a raw water cooling system) thanks for the help

 

[Zackman]

Re: engine water pump hose to hot

Eric that hose is going to get too hot to put your hand on. Beg, barrow, or buy an infarred heat gun and take some readings. It shouldn't be any hotter than your temperature gauge reads... say 170 F +/-​

 

[eric b]

Re: engine water pump hose to hot

yea that sounds like a good idea but why would that be the only hose that hot and is there some where i can find a water flow diagram to see how it flows throught the hole system thanks for the help

 

[Anchor Management 1]

Re: engine water pump hose to hot

sounds like the recirculating (on eng.) pump is not working properly.

 

[eric b]

Re: engine water pump hose to hot

i toke the pump off of the engine and removed the cover from the back and the impeler looks ok no damage and it spins with the shaft

 

[cooter2506]

Re: engine water pump hose to hot

Your clue is in the temp guage. What temp was it running? More than likely if temp was ok everything is fine. But get a temop gun and measure everything. Risers, exhaust manifolds, water hoses, and take a temp at the guage sender just to check guage accuracy. Oh and by if you are doing this at the last launch by the dam at Lake Clarke watch out for all the HUGE floaters out there. I went out on Saturday and it was horrible with floaters. Lots of debris.

 

[eric b]

Re: engine water pump hose to hot

i was out saterday to i put in at the first ramp with my other boat. so back to the problem if i let it idle for like 15-20 min what should the temp be at on the gage and on a temp gun?

 

[cooter2506]

Re: engine water pump hose to hot

It robably has a 140 tstat so somewhere around 140 on the guage and at the sender. Havent checked my risers yet on my 4.3. But my 5.0 on my other boat ran about 140. But next time out I will check my riser temps.

 

[maddog2]

Re: engine water pump hose to hot

I am not a certified marine mechanic, but I was told by someone that you could run the engine without the thermostat.
It could also be that the thermostat hasn't opened up to allow the water to circulate.
I would let the mods of this forum give you some sound advice first.
I really dont know what effect it would have on your engine without a thermostat, except it may take a little longer to warm up.

 

[eric b]

Re: engine water pump hose to hot

when i had it idleing the temp was at like 160-170 in like 15 min on the gage that seems high to me. i pulled the hose off comeing from the outdrive pump and there was water comeing out but it wasent like a masave amount

 

[eric b]

Re: engine water pump hose to hot

i am also not a marine tech but i was told if you remove the t-stat that the water wont have enough time to suck the heat out of the engine even though the gage says its cold the engine is realey hot but thats just what i was told

 

[cooter2506]

Re: engine water pump hose to hot

Run it on muffs at home and see if you have good water flow out the idle relief ports on your gimble housing. Let it idle and check your guages. See what it registers. I will look to see what tsat should be in there. But do NOT run it without a tstat. Not sure why but I know the higher ups on here say not to do it. Go up to the adult stickies section at the top of this forum. Download the manual for your engine and drive. Lots of good FREE info in there

 

[maddog2]

Re: engine water pump hose to hot

I have a 1992 Mercruiser 4.3LX. It is currently being replaced with a new long block. The mechanic working on the boat said he always takes out the thermostat on his own engines. My thermostat was frozen in place and wouldn't open up to allow the cooler water to enter the block.
My guess it that if the water pump is circulating fresh water through the block, then it should stay cool.
I see your point about water passing through too fast to actually cool the engine.
Good luck.

I just purchased a remanufactured 4.3L long block with the heads for $1,300.
add another $1,200 for removal and installation.

www.rapidomarine.com is where I found the engine.

 

[cooter2506]

Re: engine water pump hose to hot

Just thought of something. You say it has a new impeller in the outdrive. Did you just change the impeller or the entire housing, upper and lower.?

 

[eric b]

Re: engine water pump hose to hot

the impeler is new and the housing is in grate shape also the pipes are all in good shape. is there a rite or wrong way to put that impeler in

 

[cooter2506]

Re: engine water pump hose to hot

Only thing that is important is when you slidethe top housing over the impeller , you turn the drive shaft clockwise to ease the impeller into the housing.

 

[Backyardhockey]

Re: engine water pump hose to hot

No expert but.....you want a thermostat. Engines are designed to run at a certain temp and the thermostat helps that happen. No thermo means It will run cooler. Your engine will not be running at peak performance so you will be wasting fuel. Your oil will be more contaminated causing some internal nastiness. Or I'm totally wrong.