J90ELEDR Cooling Concerns

[Big Jay]

Hello again to all, this is a bit long winded, apologies ahead of time!

I'm the 3rd owner of a J90ELED 1996 90hp Johnson with the 60⁰ block. The engine is in fantastic shape inside and out, it's been very well maintained and cared for. It has been a freshwater beast its whole life here in Ontario Canada, and after changing the plugs (130psi in all 4 jugs) and rebuilding the fuel and OMS systems, she runs beautifully and reliably.

I do however have one issue that had been plaguing me: the cooling system.

I'd installed a full impeller kit, and she pumps water nice and strong, but I was still seeing varying temperatures, just a bit too hot to be considered ok.

I then swapped out the thermostats, but at the time of purchase was somehow not told about the related thermostat seals. That said, when I removed the original thermostats, I found no seals in the assembly other than the O-rings on the large plastic nuts. So I thought maybe the previous owner has forgotten to install them.

I source new ones, put them on the engine-facing end of the thermostats (seemed like a no-brainer) and reassembled. It ran much cooler at this point for a trip or two, but now I'm finding a hot block at the end of the day again. Not hot enough to set off the alarm, but I need to remove my finger after 4-5 seconds.

I double checked the parts-explosion pic online, and I'm now seeing that the seal (#26 in the pic, a rubber covered metal washer) seems to be installed "between" the cylinder head, gasket, and the block!

Can someone please confirm or deny this?

If this isn't the case, the original seals could've easily fallen down into the water jacket when removing the thermostats, and could be providing restriction of water flow causing my intermittent overheating...

I have a full engine gasket kit on hand, and can easily pull the heads and rectify this, should this be the case..

Any direction or advice would be greatly appreciated!!

 

[tphoyt]

Do you have an IR temp gun to get an accurate reading? I’m not usually a fan of cheap tools but I have have an $8.00 gun and $70.00 gun and they both work the same so in this case chep has worked for me. It’s a very helpful tool. It’s hard for any of us to help find a blockage if you think that’s what’s happening.

 

[Big Jay]

Do you have an IR temp gun to get an accurate reading? I’m not usually a fan of cheap tools but I have have an $8.00 gun and $70.00 gun and they both work the same so in this case chep has worked for me. It’s a very helpful tool. It’s hard for any of us to help find a blockage if you think that’s what’s happening.

I do, she was reading upwards of 107⁰ Celsius before I installed the missing seals. Way hot.
Once the seals were in it read around 40-70⁰ on the good days, but back up in the high 90⁰'s on others.

I really just need to know if I've got the seals installed in the right place. If so, then I'm thinking the originals may have fallen down into the water jacket, due to my ignorance. I simply didn't know they were there lol.

There's a guy on YouTube with the 150hp 60⁰block from the same model year who posted a vid changing his thermostats, but I saw no indication of any seals while he did this. Same style 'stats as mine, same large plastic retaining nuts and springs.

Furthers my suspicions that the seals are between the block and cylinder head..

Just looking for confirmation before pulling the heads on mine.

 

[saltchuckmatt]

Can't really answer your question but if you're running that hot and your alarm is not going off you have something wrong and the alarm system. Is the control box horn giving you one beep at startup? Otherwise test the sensor on the heads.... Easy to do.

I'm surprised you can keep your finger on the head for four to five seconds with that kind of heat

 

[Big Jay]

Can't really answer your question but if you're running that hot and your alarm is not going off you have something wrong and the alarm system. Is the control box horn giving you one beep at startup? Otherwise test the sensor on the heads.... Easy to do.

I'm surprised you can keep your finger on the head for four to five seconds with that kind of heat

Alarm self test beeps without issue, all lights function. I think the manual says the heat alarm goes off around 117⁰C, but it's yet to trigger for me. It's also possible my estimation of upper 90⁰s may have been high, I didn't have my temp gun with me after the first couple runs that it stayed cool, as I'd thought I'd had it licked.

Manually touching the engine after that first seemingly misleading "cool" run or two, the block was what I expected.. luke warm to the finger touch, slowly warming a bit more once the water drained after trailering the boat, but never hot enough to make me pull my finger away. The subsequent runs I found i could only hold my finger there for a few seconds, and that was moments after pulling it from the water.

 

[Big Jay]

Anyone know the correct orientation of the thermostat seals on this engine?