1989 Crossflow Thermostat Question.

[mattkenton]

Ok so i was running the engine on the muffs yesterday and i touched the port side of the block and it felt a little warm, not bad. Felt the starboard side and it about left a blister. I turned off the engine and opened up the thermostat housing. Thermostat was dry on the backside that opens up. But my tell tale was peeing just fine. Should the tell tale pee if the thermostat is not opening? I think it is time to replace both thermostats just to be safe. They are super easy to get to.

I looked inside and did not see any major salt build up. Just a slight bit of wall crud. Maybe a mm or so.

I am def going to replace the thermostat but would like to test it to confirm my theory of it not opening up. Do i do this just like a car thermo, in a bowl of boiling water with a thermostat?

Thanks.

 

[DargelJohn]

Re: 1989 Crossflow Thermostat Question.

"Do i do this just like a car thermo, in a bowl of boiling water with a thermostat?"

Yes, They should start opening around 140 degrees.

 

[mattkenton]

Re: 1989 Crossflow Thermostat Question.

"Do i do this just like a car thermo, in a bowl of boiling water with a thermostat?"

Yes, They should start opening around 140 degrees.

Ok thanks

 

[mattkenton]

Re: 1989 Crossflow Thermostat Question.

So I tested the thermostats and the hot side one did not open. What sort of damage might I have done? She was running great the last time I took her out. Hope I caught it in time before anything major.

 

[emdsapmgr]

Re: 1989 Crossflow Thermostat Question.

You can have a strong telltale and still have an overheat if one of the stats is stuck closed. When one sticks shut, it won't permit the water to circulate through that side of the engine. The stats open at 143 and should idle between 143 and 150 or so. In warm lake water in the summer, it could idle at 155. Replace both your stats and recheck your running temps. If you are concerned about any damage to the powerhead, compession check it and compare the cool head side numbers with the overheat side numbers.

 

[Bob_VT]

Re: 1989 Crossflow Thermostat Question.

Thermostats and water deflectors go bad in V-4's and should be changed. You will see a great improvement. Why take chances? Yes a tell tale will pee with and without the thermostats working since it is fed from the block.

 

[mattkenton]

Re: 1989 Crossflow Thermostat Question.

Thanks guys. I replaced them and they are both coming up to the same temp now. Thanks for all the help. Cheers!