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Discussion Starter #1
A little backstory. When I bought my '68 the previous owner had dropped in a 351C 2V. But for some reason he had put a STANDARD 180 degree thermostat in it. I couldn't figure out for the life of me why the temperature would rise so quickly in traffic until I looked at it. When it came to fixing it however I opted to go with these parts below instead of a new Cleveland thermostat since I've heard many times that the original design is flawed.

http://www.cougarpartscatalog.com/waterrestrictplate.html
http://www.cougarpartscatalog.com/rt-351.html

But after putting the restriction plate and brand new thermostat in my engine runs cold!! It won't top 160 now. Any ideas of what could be wrong or what I should do?

This car is my daily driver so I really need to figure this out. Thanks in advance.
 

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Interesting info on the new plate and the regular T-stat. Can't say I have ever found (or even heard) the original system to be flawed and even my newest Cleveland whose cooling jackets are half-filled with Hard-Blok (a sort of concrete) runs normally with regard to temperature.

If I was in your shoes, I would be wondering what the situation would have been if you had left the original plate and put the correct T-stat in.

Mike, any other Cleveland guys care to comment?

Regards,

Bob
 

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Discussion Starter #3
If I was in your shoes, I would be wondering what the situation would have been if you had left the original plate and put the correct T-stat in.
I very much have been wondering that haha.
 

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I have always been skeptical of the plate, but have pondered trying it. The thing that I don't like is that the original was designed to let coolant flow around the block and heads before the T-stat opened. Once the thermostat opened it would block the bypass of and "work" like any other engine. The bad about that was that the "hat" didn't seal up to the bypass well many times and that is why they would run hot. Sometimes it wouldn't seal centered at all and would keep the thermostat from openeing all the way, thus working on bypass all the time with restricted radiator flow. The bad thing about the plate that Don sells is that it doesn't let coolant flow before the T-stat opens, causing brief hot spots before you get good coolant flow.

If I ever do have an issue, which I haven't in 300 miles yet, I will get one of these and try it.

On the trying it the factory way, could never hurt to have both setups around anyway. The C T-stat does cost around 20 bucks though.
 

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Where do you get the temp of 160*?
If it's from an aftermarket gauge, then that don't mean nothin' until you verify it with a real temp reader.

Heat the t-stat in water on the kitchen stove while observing and recording what temp makes it start to open.

I use a meat or candy thermometer, depending on the temp range.
 

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Discussion Starter #6
Well now I have a bit of a dilemma as I kinda had to ruin the original brass plate to get it out...

So since going back to original wouldn't be cheap for me now, does anyone have a suggestion as to what I should do?

Cougarshaman, would testing that give me an accurate idea of operating temperature though?
 

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Yeah, it will.
Mostly it's an indicator of whether or not it opens at prescribed temp. Things get boxed wrong and built wrong all the time in factories. Especially small or short runs of specialty parts, like t-stats for relatively obscure 40 year old v8 engines.
Double checking the opening temp for it takes the most simple solution out of the equation, namely that it's simply just a bad stat.
 

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Well now I have a bit of a dilemma as I kinda had to ruin the original brass plate to get it out...
I didn't study it in detail but I think you might be able to drill out the "improved" type to mimic the original type.
 

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Discussion Starter #9
I didn't study it in detail but I think you might be able to drill out the "improved" type to mimic the original type.
That's what I was thinking. But first I'm going to do as Cougarshaman suggested. Thanks guys.
 

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If that test looks good - may want to wonder if your temp guage is showing actual temp? Most clevo's have overheat trouble not cold..just sounds fishy.
 

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Well now I have a bit of a dilemma as I kinda had to ruin the original brass plate to get it out...

So since going back to original wouldn't be cheap for me now, does anyone have a suggestion as to what I should do?

Cougarshaman, would testing that give me an accurate idea of operating temperature though?
I would like to see the results of what going back to the original versus our "upgrade" will do. Call us, we have plenty "mint" originals in stock. If you want a reproduction of the original brass unit, "GOOGLE" DOAZ-8K517-A. The upgrade really is a miracle cure guys, "GOOGLE" Pantera Restrictor or divertor plate and you will see what I mean.

 
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