Evinrude running hot to the touch

[iggyw1]

Hi guys,

I just picked up an Evinrude motor, 1965 model #75553, 75 H.P. Took the boat out to the dock today. Did not take it off of the trailer and started her up. Started great and ran wonderful, but I had the cover off and felt the top of the upper pistons housings and they felt really hot. I came home, removed the lower unit to inspect the water pump and all looked like a new pump and housing, seals grommets etc. Could see no problems at all.

I checked and tested the thermostat and it seemed fine. I blew air thru the water tubes and got no resistance from it. I have ordered a new pump kit and gonna replace things again even though the parts all looked good. The old owner started the boat a few times with no water he told me. How difficult is it to check the water passages on this motor? I would like to check them out to see if they are clear, but I am really not sure what I need to take apart to do this. Do I need to take off just the round cover where the spark plug is screwed into or do I need to take off the part behind this part? It has bolts in it too. The piston heads should be cool to the touch correct? I could only hold my hand on it about three seconds and it was too hot to touch so I shut the motor off at that point.

Could the impeller be fried even though it looked good because the past owner ran it with no water?? I also saw no water spraying out of the water exhaust while I was running it.

 

[Bosunsmate]

Re: Evinrude running hot to the touch

To look at all the passages you need to take off all the covers/exhaust/head/cylinder cover/remove the powerhead, water closet on top and there is possibly a few others.
You could remove one of those rear outer cylinder head covers and see what it looks like in there before deciding to go any further.

Impeller could be fried hard to tell without having it in my hand.
You need to make sure you have the trailer/motor quite deep in the water to get water into the pump. If the water level wasnt high enough you would be sucking air in so itd overheat then

 

[71Windsor]

Re: Evinrude running hot to the touch

How did you check or test the thermostat?

 

[iggyw1]

Re: Evinrude running hot to the touch

Windsor: I tested the thermostat by taking it out and I put it into water that was 150 degrees on an oven thermometer. It opened. Then I set it into a glass of cold water and it closed. (with a little bit of pressure with my fingers as I figured the spring inside the housing would do that too). Of course the pressure applied would probably be different, but I know when I ran the motor the stat did not stick 'open'.

 

[iggyw1]

Re: Evinrude running hot to the touch

Bosunsmate: I have a new pump kit on order. Has the impeller, housing, seals, 'o' rings etc. I am going to replace it all. The kit runs $260 locally here , but I found it on e-bay (new of course) for $65 w/delivery. Could not beat this price!! Sounds like more than I can handle to check the water passages. WOW! The trailer was deep enough into the water for sure.

Before I do anything else, I will wait for my kit to come in and replace the pump parts and try it out again. Thanks!

 

[71Windsor]

Re: Evinrude running hot to the touch

Then your next step is to check the water pump. When you had the thermostats out did you start the engine to check for water making it to the top? Usually how I verify a water pump quickly.

 

[iggyw1]

Re: Evinrude running hot to the touch

No I did not do that. I am thinking right now to put my new pump parts in when they arrive. Then go to the lake and try it out. If it is still getting hot, I will remove the thermostat since that is nice and easy to do right at the lake. If it solves the problem, I will get a new thermostat (which I found out on my motor is called a VERNATHERM, NOT a thermostat. A bit of a difference how it's made). And I also found mine should POSSIBLY open at 105 degrees NOT 140 degrees.

If anyone can find the part number for my VERNATHERM, I would appreciate the help. I cannot locate the part number and there are a few of these VERNATHERMS for the Evinrudes. 1965model # 75553, 75H.P. Speedy four (standard). Thanks again!

NOTE: I talked to a mechanic today, he told me that the most likely place for the water passage would be plugged on my motor would be a plastic tube at the top of the water tube directly beneath the power head. He said if the guy ran it long enough with no water, (the previous owner), this plastic piece could have melted and plugged the water tube up. I blew air thru the tube today with a compressor, and it seemed ok. He said it probably is good then, so he said it sounds like just the water pump or vernatherm.

 

[Solittle]

Re: Evinrude running hot to the touch

This calls for an infra red temp gauge to get actual readings. Great to have in your tool box.

 

[Bosunsmate]

Re: Evinrude running hot to the touch

You can hook a hose up to that inlet tube, dont put it on the highest pressure, just a couple of turns of the hose should be enough.
You can then run the motor and see if it overheats.
I normally start the motor and then turn the hose on as having water flowing in there can make it harder for it too start by being a bit cooler.
I do this often. You can leave the motor running for as long as you want doing this to check for overheating. My normal garden hose fits on all the motors ive done this on very easily. Sometimes i wrap a bit of tape around the water tube bottom to make it a bit thicker but thats all thats needed.

Doing this you remove the water pump from being the issue for overheating if it still overheats

 

[iggyw1]

Re: Evinrude running hot to the touch

This calls for an infra red temp gauge to get actual readings. Great to have in your tool box.

I did buy one. Anxious to try it out when I get my pump back together. Waiting on the parts to arrive.

 

[iggyw1]

Re: Evinrude running hot to the touch

You can hook a hose up to that inlet tube, dont put it on the highest pressure, just a couple of turns of the hose should be enough.
You can then run the motor and see if it overheats.
I normally start the motor and then turn the hose on as having water flowing in there can make it harder for it too start by being a bit cooler.
I do this often. You can leave the motor running for as long as you want doing this to check for overheating. My normal garden hose fits on all the motors ive done this on very easily. Sometimes i wrap a bit of tape around the water tube bottom to make it a bit thicker but thats all thats needed.

Doing this you remove the water pump from being the issue for overheating if it still overheats

This sounds like a GREAT idea!! I assume you are talking about starting the motor without the lower unit or drive shaft even hooked up correct? I wouldn't want things to go flying out or anything on me, so I will wait 'til you answer to this before I do it. If it does still heat up that way, I can remove the T-stat and try it again to see if that is bad correct?

 

[ronward]

Re: Evinrude running hot to the touch

You can run it like that but I would make sure the neighbors are awake before starting it. Without the lower unit installed and no water diluting the exhaust you are effectively removing the outboards "built-in" muffler. Ever heard a lawn mower with the muffler blown out???

 

[iggyw1]

Re: Evinrude running hot to the touch

Sounds right to me, so I will make sure the neighbors are up and I will let them know I will be making some noise and smoke too. I have some very good neighbors next to me, across from me and a few doors sown each way! Thanks for you input. I know the thing is loud even with the lower unit in place with just a hose hooked up to it in the driveway. I should still be able to feel some heated water leaving the motor from somewhere right??

 

[ronward]

Re: Evinrude running hot to the touch

the water coming out might be a little warm but not much due to a constant stream of fresh cool water going in. main thing ur looking for is if head still gets too hot.. if the head still gets super hot then you will know the problem is not the pump because you have bypassed it. there would have to be a blockage. if water comes out then the water tube is open (or at least partially, judge for yourself by how much comes out)

 

[71Windsor]

Re: Evinrude running hot to the touch

Just an fyi if you do remove the thermostats to test that water is making its way up to them don't run your motor with out the thermostats. This is just to see that water is certainly making its way up there and that the water pump is getting it up there. Your engine requires a pretty precise temp to run at and yes it can run to cold with the thermostat out of the engine. Running it to cold will not efficiently burn the fuel and oil which created more operating issues.

 

[gm280]

Re: Evinrude running hot to the touch

When you did the lake start and hand on the engine, did you see any water coming out of the exhaust with the smoke? Could you see any water in the exhaust at all? Or do you have a pee tail tube on that engine? Also, did the engine run long enough for the thermostat (VERNATHERM) to actually open? It does take a little longer for that to operate correctly, some times a few minutes. Before changing anything, do a little more testing with water muffs or at the lake. Could be nothing is wrong...

 

[Bosunsmate]

Re: Evinrude running hot to the touch

This sounds like a GREAT idea!! I assume you are talking about starting the motor without the lower unit or drive shaft even hooked up correct? I wouldn't want things to go flying out or anything on me, so I will wait 'til you answer to this before I do it. If it does still heat up that way, I can remove the T-stat and try it again to see if that is bad correct?

Yes and good that Ronward pointed out the neighhbour issue, in case they had a easter meditation plannned.
Heres a video of me my friend put up on youtube doing it to a yamaha at home. I live on a farm so no neighbour problem here, the closest neighbour is a quarry.

https://www.youtube.com/watch?v=_VVWEhhfuuE

Just keep an eye that the hose hasnt popped off the water intake. i often push my hose the whole way up that itl go.

 

[Bosunsmate]

Re: Evinrude running hot to the touch

Just an fyi if you do remove the thermostats to test that water is making its way up to them don't run your motor with out the thermostats. This is just to see that water is certainly making its way up there and that the water pump is getting it up there. Your engine requires a pretty precise temp to run at and yes it can run to cold with the thermostat out of the engine. Running it to cold will not efficiently burn the fuel and oil which created more operating issues.

Yes definitely heed this advice too, you can end up with a cold seize

 

[iggyw1]

Re: Evinrude running hot to the touch

When you did the lake start and hand on the engine, did you see any water coming out of the exhaust with the smoke? Could you see any water in the exhaust at all? Or do you have a pee tail tube on that engine? Also, did the engine run long enough for the thermostat (VERNATHERM) to actually open? It does take a little longer for that to operate correctly, some times a few minutes. Before changing anything, do a little more testing with water muffs or at the lake. Could be nothing is wrong...

I do not have a pee tail on this motor, and I did not see water coming out with the exhaust at all. I ran the motor about three minutes is all, until I felt it was too hot to run. I could hold my hand on the upper cylinder head on the starboard side for about 2-3 seconds and it was HOT.

I cannot do any more testing at the lake until I do the pump replacement. I am set to do the pump kit replacement because I have the motor torn apart now and the parts have been ordered and should be here on Wed or Thursday of this week (week starting 4-21-14). I cannot use muffs on this motor as it does not have the side water pick ups. It has a screen at the bottom beneath the below water exhaust outlet, so it has some kind of special water fixture I would imagine (if any). I will try what I read earlier on here to run the water tube pickup into a garden hose and run the motor with that water supply thereby bypassing the T-stat. (Vernatherm) Thanks for your input.

 

[iggyw1]

Re: Evinrude running hot to the touch

I understand that running the motor on a regular basis without the thermostat is bad news for the engine. According to my repair manual though, it states if need be, the thermostat can be removed out on the lake if it is stuck in the closed position, can be driven back to shore for a few awhile at below WOT, but "Be sure to replace the T-stat before heading out onto the lake again". So it would appear to me after reading this that it would be ok to run the motor without the T-stat for a minute or two to see if the head stays cool (cold), then shut it down and install a new T-stat if that was the problem. I know for this short few moments my economy would be effected and the oil and gas would not all burn up, and the plugs may foul a bit, but as soon as I replace the T-stat and run the motor wide open on the lake, I think the carbon would burn off, correct? Thanks for your input.