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318 Thermostat Question

J

JJDebeers

Regular Contributor
My stbd motor (RWC) has a 1974 "top hat" style thermostat and housing. The motor can't seem to get to normal operating temperature, even after 30-45 minutes at 2500 RPM. The manifolds and risers reach just over 100 degrees, but the intake manifold (near the temp sender) barely reaches 100.

I removed the housing and thermostat to inspect. The thermostat is not stuck in the open position, and I noticed that when the thermostat is seated in the housing, there is actually a gap the top of the thermostat body and inner surface of the housing. Therefore, even if the thermostat is closed, water can still flow through this gap, down the inside of the thermostat body, and into the engine block.

I am under the impression that there should be some type of seal on the inside of the housing which allows the thermostat body to "seat" into and create a water tight seal. I've attached some images if anyone cares to look.

Any suggestions?


-JJ2012-05-24_17-19-22_574.jpg2012-05-24_17-18-48_70.jpg
 
Been there, had that prolem, fixed it.

Due to rusting, the water is bypassing around the t-stat, which keeps the motor cold (and empties yur wallet quicker at gas ups!) The solution is make a metal plate (stainless) that resembles the gasket and epoxy/ rivet the t-stat to this plate. Use a gasket above and below, and that motor will warm right up!

Jeff

PS: Using this technique, one can also use the smaller daimeter (and cheaper!) t-stats.
 

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Jeff,

There's no corrosion between the t-stat and the intake manifold. The intake manifold is only a few years old. I think my problem is with the clearance between the top of the t-stat, and the inner surface of the t-stat housing.

I'm not sure if your solution would work in this instance.

Thanks,
JJ
 
Rust where the t-stat fits into the manifold. Mine are so bad the t-stat is gotta be rattling loose when assembled.

Jeff
 
sure are alot of holes in the bottom side of your t-stat JJ, dosent look like jeffs original on the right of his SS plate contraption!!

looks like a weird t-stat is my suggestion,after you clean up all that rust in the housing put the right 143 in make your own gasket to fit your intake and cut it just right so it ovelaps the first edge of the t-stat, you may want to do a double gasket samich if the mating surfaces have had enough or mill it
 
Jeff, is yours also a top hat style or the newer flatter style t-stat? When I pulled the t-stat I did notice that the design was very slotted. It didn't make sense to me why it would be so slotted if it was designed to hold water back....At first I thought maybe it was an automotive t-stat, but it has "145" stamped on it. I don't think auto t-stats were made to open at that low of a temperature.

The mating surfaces on the manifold and t-stat housing look great. The motor has barely 50 hours on it. I'm confident that water is getting by the t-stat. My only unknown was is it the gap at the top between the housing and t-stat or is it the slotted design, as you pointed out.

Anyway, I just picked up the kit to convert to FWC. This includes a new t-stat and newer style housing (3 inlet). My plan was to wait until Fall, but maybe I'll get it done sooner instead of messing with the current setup.

Thanks,
JJ
 
JJ, for what this is worth..... many of these T-stat housings deliberately by-pass to a small degree..... the Ford 5.0L and 5.8L for example.
I see that you are no longer raw water cooling this engine, but if you should come upon this issue again, try swapping the port for the stbd housing and stat, and giving it a try?
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As for coverting a previously raw water cooled engine over to a closed cooling sytem, be sure that you understand the risks in doing so.

The first 10-20 hours of operation may pose no issues, but after that, any rust scale debris will begin to build up around the E/G side of the tube bundle, reducing it's heat exchange ability.
I recommend to people doing this, that they remove the H/E at 20-30 hours, or so, and dump the contents into a white bucket, and examine the amount of rust scale debris.
Re-install..... run for another 20-30 hours, and repeat.
Continue doing this, until the debris is minimal.

The E/G side of the tube bundle is not user accessible, and you sure don't want this side to become restricted.


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ALL motors have some tyoe of by pass or the circulating pump would cavitatge itself to death.

There should be NO bypass holes in your t-stat, however; that's what the hose in front of the manifold is for.

Jeff
 
Ricardo,

I think you misundertood, I AM currently RWC that engine (stdb). I have purchased the necessary components for FWC, but have not yet installed. My other engine (port) is FWC already. The previous owner converted it, but not the stbd.

Since the port engine is FWC, I don't want to mess with the t-stat or housing. It also has a different style t-stat housing anyway, the three inlet newer style housing. I plan on rinsing the block several times with "salt away" before I do the conversion. This is what was recommended by many when converting an engine from RWC to FWC.

Jeff, do you have the top hat style t-stats or not???
 
JJDebeers said:
Ricardo,

I think you misundertood, I AM currently RWC that engine (stdb). I have purchased the necessary components for FWC, but have not yet installed. My other engine (port) is FWC already. The previous owner converted it, but not the stbd.

Since the port engine is FWC, I don't want to mess with the t-stat or housing. It also has a different style t-stat housing anyway, the three inlet newer style housing. I plan on rinsing the block several times with "salt away" before I do the conversion. This is what was recommended by many when converting an engine from RWC to FWC.
Click to expand...
JJ, you are correct. My boo boo.
I did not catch the part about the Port engine having already been converted to a Closed Cooling system.
And yes, the thermostat housing would be considerably different between the two systems.

With that exception, I'll still suggest:
  • if in the future, with twins we have the ability to swap some parts, and usually with ease (although not in this case).
  • as for the newly converted RWC engine to a CCS engine, I still maintain that you inspect the E/G side periodically and for the first XX hours.


,
 
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The pictures look like the seal has gone inside the housing..the thermostat should be a tight friction fit, if not its going to leak & let the water run right out
 
..."Jeff, do you have the top hat style t-stats or not??? "

Didn't answer you 'cause I'm not sure what that means.

Jeff
 
On your housing, maybe you could have some material milled off the face to tighten the fit up. Make sure there is .003" for the t-stat flange to "float" in so you don't crack the housing when tightening the bolts.
 
The entire t-stat fits up inside the housing with this style. There is no flange between the housing and manifold. Besides, the gasket creates all the clearance you need. No need to go mill a .003 clearance into a piece of cast. The casting tolerances are probably 3 times greater than that.
 
Sorry for my Ignorance but, what are the advantages letting your engine heat up and not running it as cool as possible? How and why does it eat more gas on a carb engine? Thanks
 
Higher temperatures allow the engine to atomize and combust the fuel more efficiently resulting in more power and less fuel consumption.

-JJ
 
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