62 18hp cooling question

[sluggo99]

Must be the full moon causing all these temperature questions? Anyway, my 18hp is overheating. According to my harbor freight IR laser temp gizmo, over 190 degrees, but more than that measurement, it just seems way too hot.

This is a 62 powerhead on a 67 'everything else', if that makes any difference. It's an ebay powerhead I've just installed. I've also replaced the impeller and thermostat. I've not taken the head or exhaust cover or anything else off the PH, but compression test was ~93/98

Plenty of water coming out the exhaust. I'm running it in a big trashcan with water way up high on the LU.

I pulled the thermostat cover when it was still hot, and the thermostat was open, so I figure that's OK. I put it all back together, started it, and pulled the thermo cover while it was idling. There was a small amount of water kind of 'popping up' from the smaller round hole under the thermostat cover. The larger hole, the one for the thermostat itself, was dry, though.

I thought the pressured water from the impeller would be coming from under the thermostat? Is this not where the water comes into the head? If it IS supposed to coming from the smaller hole, how much should be coming out at idle? Sure didn't seem like much.

I'm thinking I may have to drop the LU again, to see if the grommet got goofed, but would I have good water stream from the exhaust if this were the case?

 

[hawkf250]

Re: 62 18hp cooling question

Sounds like you have a restriction in the powerhead its self, try pulling the lower off, take a water hose and put it in the large hole in the thermostat housing and pressuring water through the block, watch to see if anything blows out of the block. if it still wont flow, you may have to pull the head and exhaust plate the try to find the restriction. Also if the previous owner never flushed the motor out, it may be so corroded that water cant get through, if so not much you can do. You mentioned that the powerhead is a different year that the rest, did you make sure that the water tube matched up with the water inlet on the powerhead? i know some of those earlier motor had the same powerhead bolt pattern but the powerhead itself was configured differently.

 

[sluggo99]

Re: 62 18hp cooling question

I feel dumb, but I didn't really look at anything very closely other than the metal pan gasket, and it seemed to be identical (I think... ). Somewhere, I had heard that a 62 and a 67 shared the same powerhead, so I took things somewhat for granted. Mistake #128.

I did run into at least one strange issue. The 62 thermostat cover is different from the 67. I attached some pics that compares them. I can't see a functional difference, but there's evidently something going on there.
-The '62 cover is thicker than the 67
-The '62 cover has an extra hole where the 67 has a flat sealing surface to the head.
The hole is blind on the 62 cover, going to an untapped outlet (?).
At the head to cover mating surface, the hole is open to a hole on the head.
The 67 head does not have this hole at all.

If I had to guess, I'd say the hole on the 62 was a place for a tell tale or temp sender, but that's just a wag. I hope this description makes sense, or the pictures explain it.

One more weirdness clue; the local OMC guys said the thermo cover gaskets were the same for 62 and 67. They obviously aren't in my case, at least. Maybe there's something else going on here? Maybe the ebay 62 came from bizzaro-world. lol!

In any event, I'm probably going to have to pull the powerhead off. One extra question. Is the water supposed to come up from below the thermostat? Is that the flow path? Or is it from the void under the thermostat cover down, passed the thermostat? I was not getting any water coming up from the thermostat hole, and I wasn't clear if that was abnormal.

Thanks!!!



You mentioned that the powerhead is a different year that the rest, did you make sure that the water tube matched up with the water inlet on the powerhead? i know some of those earlier motor had the same powerhead bolt pattern but the powerhead itself was configured differently.

 

[jbjennings]

Re: 62 18hp cooling question

You should surely have water coming out all over the place if the thermostat cover and thermostat are out, and the motor is running. How high is the water in your barrel? If it's not high enough, it won't prime the pump. THe water needs to be about 3 inches below the exhaust relief in the back of the midsection.
good luck,
JBJ

 

[sluggo99]

Re: 62 18hp cooling question

Yeah, I thought water should be coming out of the top of the motor at a pretty good clip. It's coming out, but only sporadically and anemically from the small hole opposite the thermo ( marked 'water' in the attached photo).

The motor is in a trash can to a depth almost to the exhaust ports. The exh ports have good water pumping out, so I think the impeller is moving water pretty good. Just seems to not be going through the head right.

I dropped the lower unit, and hooked some vinyl tubing to the metal water pipe. The water shot right up to the head, and came out the small hole directly next to the thermostat (marked 'hole' in the pic) . When I put my finger over that hole, the water came out the hole the thermostat sits in. That seems right to me. For some reason, when it runs, water does not come through this hole.

I think the question I need to answer is 'why is water coming out my exhaust ports, but not going up through the head/thermostat?'. I'm running out of ideas at this point. I'll soon have to at least pull the head.

 

[Daviet]

Re: 62 18hp cooling question

If you are getting good flow out of the thermostat housing using a hose, and it just bubbles up when the lower unit is pumping the water up, I would take a good look at the water pump.

 

[sluggo99]

Re: 62 18hp cooling question

I pulled the pump housing cover and looked at the impeller. Everything looks pretty normal. The only thing that surprised me is how small the shaft pin seems in relation to the notch in the impeller, but I guess that's how they are designed. The pin in the kit was the same as the one that was in there. The impeller is surely spinning. I can see marks in the wear plate.

I'm going to put it back together today and see if some magic happened to make it suddenly work for no apparent reason

 

[jbjennings]

Re: 62 18hp cooling question

If it were me, this is how I'd go about solving the problem:
1. I'd take off the lower unit and hook up a garden hose to the upper water tube and run the motor like that, seeing if water was flowing correctly and keeping the motor cool.
2. IF so, I'd look at the lower unit, if not, I'd take off the powerhead and make sure all the base gasket holes are where they should be, and as said, that the upper water tube was matching up where it should at the block. The bolt holes can be identical, while the base gaskets and water passages and such can be different. If a gasket in the new powerhead is blocked where it should be open.......
3. If the base gaskets and new block stuff looked good, I'd take off the head and check all the passages and find the blockage.

That's about all I'd know to do.
Good luck,
JBJ

 

[BigB9000]

Re: 62 18hp cooling question

I hate the 18/20hp
every one I have owned has had this exact same problem.

When you reinstalled the powerhead, did you buy a new gasket?
did you use any RTV?

When you re installed the water pump, did you seal the wear plate to the gearcase?

When I cleaned my powerhead, I stuck a hose in the thermostat area, and blew tons of sand out from the copper tube. then stuck the hose into the copper tube, and watched sand exit through the thermostat hole.

You might want to give that a try.

 

[sluggo99]

Re: 62 18hp cooling question

I like your idea about running it on a hose with the lower unit off. I didn't realize that could be done. That would probably isolate the problem to one or the other.

I refit the impeller this morning hoping for that 'magic cure', where you don't think you change anything, but the problem goes away. No luck this time!! Anyway, I'll probably pull the lower unit again tomorrow and try running it with the hose connected to the tube.

Thanks for the advice, JBJ. This motor was literally in a laundry basket for about 7 years. My wife told me 3 or 4 times to put it in the garbage, and a couple of times I thought she might be right. It's actually running pretty good right now, and if I can lick this overheating problem, I'm going to be extremely happy (though I know better than to gloat ).

If it were me, this is how I'd go about solving the problem:
1. I'd take off the lower unit and hook up a garden hose to the upper water tube and run the motor like that, seeing if water was flowing correctly and keeping the motor cool.
2. IF so, I'd look at the lower unit, if not, I'd take off the powerhead and make sure all the base gasket holes are where they should be, and as said, that the upper water tube was matching up where it should at the block. The bolt holes can be identical, while the base gaskets and water passages and such can be different. If a gasket in the new powerhead is blocked where it should be open.......
3. If the base gaskets and new block stuff looked good, I'd take off the head and check all the passages and find the blockage.

That's about all I'd know to do.
Good luck,
JBJ

 

[sluggo99]

Re: 62 18hp cooling question

I hate the 18/20hp
every one I have owned has had this exact same problem.

Yikes!


When you reinstalled the powerhead, did you buy a new gasket?
did you use any RTV?

Yes. I think there were two gaskets for the powerhead. One on either side of that metal plate. I didn't RTV them, though. They were installed 'dry'.

When you re installed the water pump, did you seal the wear plate to the gearcase?

Yes, I used some Permatex gasket maker gunk.

When I cleaned my powerhead, I stuck a hose in the thermostat area, and blew tons of sand out from the copper tube. then stuck the hose into the copper tube, and watched sand exit through the thermostat hole.

You might want to give that a try.

Thanks! I'm going to try that when I pull the lower unit (again) tomorrow. I shot the hose down the hole the therm sit in, and water came out the exhaust hole, so I think the water has a path. I'm just suspicious it's a 'tortured path' at this point.

I'm coming to believe this problem is not going to go away until I pull the powerhead, and/or perhaps replace the head. I have the head from my '67 available, and it's significantly different in the water path around the thermostat. I wonder if the Evinrude designers were trying to solve a design-related overheating issue?

Thanks again for your help. It's profoundly appreciated.

 

[sluggo99]

Re: 62 18hp cooling question

OK, well, I pulled the lower unit this morning and hooked my garden hose to the water tube. Turned on the water a little bit, and started her up. She ran and ran and ran and never got too hot!!

I guess this points the finger of blame on the lower unit/impeller assembly? I may be over-thinking this, but is it possible that even though I didn't turn on the hose very high, the higher water pressure and volume of the garden hose (3/8" pneumatic hose) is overcoming some defect in the power head? I'm at a total loss as to what could be haywire in the lower unit/impeller assembly. The impeller is new. The wear plate is new. The housing is not, but it was very clean.

I think for my next experiment I'll try putting a drill motor on the drive shaft (indirectly) and see how well the impeller is pumping. I know it's pumping some water at least, because I get good water out the LU exhaust port when it's connected. If water comes shooting out the tube, which I expect, I'm plumb out of ideas at that point.

 

[14ftgrumman]

Re: 62 18hp cooling question

Had a similar problem when I replaced the impeller on my old 1959 18 (with a late 60's power head). Had to change the wear plate to get a good enough seal to pump water.

If LU is comming off, change it out.

 

[Sir Robin]

Re: 62 18hp cooling question

Is the screen over the water pickup painted over? Mine was......... If there aint no screen dirt dobbers go in and PLUG YOU UP

 

[restornator]

Re: 62 18hp cooling question

the water tube is fitted into 2 grommets, one on the lower unit, the other in the exhaust housing. This could be your magic fix. Seat the water tube in the exhaust housing first, then install the lower unit, making sure the water tube is seated in the water pump housing before you bolt it on.

 

[sluggo99]

Re: 62 18hp cooling question

Well, I took a piece of air hose and spun the drive shaft. Water did come up from the impeller housing, though I wouldn't say it was a lot of water. I decided to go ahead and pull the head off. There wasn't anything obviously bad to me, but what do you guys think? Lots of salts/mineral yuck, but OK?

I'll probably put the cyl head and thermo cover plate from my original '67 on this '62. It looks like Evinrude made some changes to the cooling path (I wonder why!! lol!) and maybe it will help my 62 to cool down. Also, the head gasket design changed. They moved the weep holes (you can see 'em in the pic). Another weird thing is the thermo cover plate. I have 3 plates, altogether. The one on the 62, which is thick and has one 'slot' to the water supply hole. then I have cover plates from a 64, and my original 67. These two share a common part number, but they are different! I'm not sure which is which, actually. But one (I think the '67) has an 'extra' slot. I'll put that one on.

So I'm cleaning up the ugly carbonized pistons and cyl/head mating surface. Going to put the 67 head on, and test it tomorrow.

Restornator; I think your description of how to fit the lower unit is how I've been doing it. The tube has always been in the exhaust housing, and I've been mating the LU up to it. I haven't pulled the tube out from the exh housing. I was kind of scared to. I was (am) afraid I won't be able to get it back in.

Sir Robin; I can't find the screen over the pickup. I was looking behind the brass purge cover. Nothing was there. Is that the place it should be?

Mike; the impeller kit had a new wear plate, so it should be working, I think?
It may get to the point where I end up getting whole new kit with the housing, which I didn't replace. It seemed fine, though ( famous last words!! . When you put the late 60's powerhead on your 59, do you remember if you had any issues with the water feed/base gaskets/tin pan gizmo mating up? I've yet to pull the powerhead, but if this latest flail fails, that's probably the next straw I'll grasp at.

 

[cajuncook1]

Re: 62 18hp cooling question

Well, I took a piece of air hose and spun the drive shaft. Water did come up from the impeller housing, though I wouldn't say it was a lot of water. I decided to go ahead and pull the head off. There wasn't anything obviously bad to me, but what do you guys think? Lots of salts/mineral yuck, but OK?

If there was a good bit of sand or mineral/salt deposits in your head (obstructing the flow of water in the water jackets, then that may be good part of your cooling problem. (That's if I read your posted comment correctly).

I have a 6hp 1967 Evinrude that was running fine and after I changed the ignition setup, but I checked the head temp just as precaution, because it was a new to me motor and it was running hot 180's with a good flow of water out of the exhaust port. Removed the cylinder head and found a good bit of salt/sand at the bottom of both cylinders water jackets and obstructing flow. Cleaned it out and put a new head gasket....now running cool. I also changed the thermostat because it was all mineralized up.

good luck with motor

 

[Daviet]

Re: 62 18hp cooling question

The last time I spun a lower unit in a bucket of water, the pump shot a solid stream of water straight up about 2 feet.
You might want to double check your pump and make sure it is sealed and not sucking air.

 

[sluggo99]

Re: 62 18hp cooling question

Well, I put the head on from the '67 (this is a 62 powerhead, remember), and it seems to be working. Yes!!!!! WOO HOOO!!!! This is soooooo cool
I wonder why my wife is not more impressed!! This poor motor was in 3 boxes a few weeks ago. Now, a mere $200 or so (oh, I bought a few tools. You know how it is...) , and joila, a running machine, Josephine!

What was it? I don't know. It could be I have a weak pump for some reason, and the better cooling design of the '67 head vs. the '62 is making up for it? It seems like the '67 head (and the new style gasket) had some definite changes that were focused on cooling. So, bottom line, I know nothing except it seems to be working now.

Daviet, I didn't see your post before I put the LU back on, so I don't know if I could have gotten my pump to shoot like that or not. I had my cordless drill on low speed. That's all the little hose link I had would handle. If I have to take the LU off for some reason (I hope not, since it seemed like it got harder to put back on each time) I'm going to check that, though.

For now, though, I just need to get the idle and slow speed jet set. WOO HOOOO!! Thank you guys for helping me get this motor back to running shape!! Next thing is the low speed jet / idle setting. How are folks hooking up a tach to these things? I've got a tach dwell meter I think can be used. 600 rpm for idle, right? I think the lower cylinder is running rich based on the carbon buildup. Woo hoo! Another problem!! This one I can live with, though.

 

[14ftgrumman]

Re: 62 18hp cooling question

Well, I took a piece of air hose and spun the drive shaft. Water did come up from the impeller housing, though I wouldn't say it was a lot of water. I decided to go ahead and pull the head off. There wasn't anything obviously bad to me, but what do you guys think? Lots of salts/mineral yuck, but OK?

I'll probably put the cyl head and thermo cover plate from my original '67 on this '62. It looks like Evinrude made some changes to the cooling path (I wonder why!! lol!) and maybe it will help my 62 to cool down. Also, the head gasket design changed. They moved the weep holes (you can see 'em in the pic). Another weird thing is the thermo cover plate. I have 3 plates, altogether. The one on the 62, which is thick and has one 'slot' to the water supply hole. then I have cover plates from a 64, and my original 67. These two share a common part number, but they are different! I'm not sure which is which, actually. But one (I think the '67) has an 'extra' slot. I'll put that one on.

So I'm cleaning up the ugly carbonized pistons and cyl/head mating surface. Going to put the 67 head on, and test it tomorrow.

Restornator; I think your description of how to fit the lower unit is how I've been doing it. The tube has always been in the exhaust housing, and I've been mating the LU up to it. I haven't pulled the tube out from the exh housing. I was kind of scared to. I was (am) afraid I won't be able to get it back in.

Sir Robin; I can't find the screen over the pickup. I was looking behind the brass purge cover. Nothing was there. Is that the place it should be?

Mike; the impeller kit had a new wear plate, so it should be working, I think?
It may get to the point where I end up getting whole new kit with the housing, which I didn't replace. It seemed fine, though ( famous last words!! . When you put the late 60's powerhead on your 59, do you remember if you had any issues with the water feed/base gaskets/tin pan gizmo mating up? I've yet to pull the powerhead, but if this latest flail fails, that's probably the next straw I'll grasp at.

Didn't put the restrictor plate on. Was too much of a hassle to try to line up everything. I did use RTV instead of a paper gasket- just remember to use a SMALL bead and let it firm up, first. My outboard guy said that the motor would run cooler w/o the plate, because of the very small outlet hole in the plate. Use all the engine parts (head, thermo housing, ect) from the new power head. Don't try to mix and match.