Thermostat and gasket for pcm 454

[Ptownkid]

So i know i need a new gasket for my thermostat in the saltare, so I e-mailed skidim about it. The only stat for a 454 is a "no longer available" stat at $100? Really?

[ssa]

Skidim did have a kit from PCM that ran $130 i believe that converted your housing over to a newer style that used regular automotive thermostats but the page I book marked no longer exists. They've got one for Indmar though that does the same thing that looks like it would hook right up in place of the pcm part. Its 109 and you still have to buy the thermostat but if you need a new one it would be good to never have to worry about getting those high dollar ones again if you can find them.

[cadunkle]

Yes they can be converted, I believe the part skidim sold (maybe still sells?) to convert is just a Mercruiser 454 thermostat housing and uses a normal automotice thermostat you can get for $10 or whatever they go for these days. I recall when I got my 145* PCM 454 thermostat it was about $45 or $75, one or the other... which I thought was pricey but realized they are special so got two in case they ever stopped making them. Ebasicpower sells a 170* that looks to fit that PCM housing. If yours has failed it should work but keep in mind if you run at all in salt or brackish you need to stay 145*-ish to protect your cooling system.

http://bpi.ebasicpower.com/pc/PLERP026001/PLE3D

[haugy]

I think once it gets to be that "time" on mine, I'll just pull the T-stat.

[wotan2525]

This question has come up on here before -- I think you can use a regular 454 automotive thermostat in the stock housing. Here's my photo of my housing and I've always just gone to the auto parts store and purchased one for $10. Fits perfectly in the little "groove" in the top of the intake. A little silicone around the bolts and base of the thermostat housing and it's never leaked. Does your housing look different?

http://i635.photobucket.com/albums/uu79/rbosworth/20130608_131207_zps3233f2b4.jpg

[Ptownkid]

That does look like it...do they carry the gaskets too?

[TitanTn]

I think I actually bought the last thermostat for the old housings that skidim had. They told me it was the last one (about 1.5 years ago) and that next time I'd have to get the conversion kit to use an automotive thermo.

Wotan - that's my original thermo housing also. Can you tell us a part number for the thermostat you're finding? My local auto parts store can only find parts by the cars listed in their system.

[Ptownkid]

They found more.

[wotan2525]

I think I actually bought the last thermostat for the old housings that skidim had. They told me it was the last one (about 1.5 years ago) and that next time I'd have to get the conversion kit to use an automotive thermo.

Wotan - that's my original thermo housing also. Can you tell us a part number for the thermostat you're finding? My local auto parts store can only find parts by the cars listed in their system.


I just go in and tell them it's a 1980 GMC C3500 w/ the 454. Looks like NAPA #THM 530060 for the 160 degree version. Here are the specs if someone wants to measure their existing one:

Attributes:
# of Check Valves : 0
# of Seals : 0
Depth from Flange : .91"
Design : Superstat
Flange Diameter : 2.125"
Height from Flange : .91"
Jiggle Pin : No
Temperature Range : 160 Deg

If I recall it comes with the gasket, but they also sell the gasket as part #THM 1053ST

[TitanTn]

That's great. I'm going to get one as a backup.


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[92SupraComp]

Why not buy a sheet of gasket and make a gasket? I did for my comp summer. Bought a new 160* to replace the tired 143* that was stuck at one spot pretty much. Had some gasket material sitting around and make one in just a minute...

[Ptownkid]

Is 180 too hot?

[TitanTn]

I believe that it is too hot for a PCM 454.

[wotan2525]

I believe that it is too hot for a PCM 454.

I don't think so. I run a 180 in mine. The only difference is that you don't have much margin for error.... with a 140 you can tell right away if the temp starts going up. On mine, if it gets up past 190 I know I have a problem but the window is a lot shorter to shut it down.

[devovino]

I don't think so. I run a 180 in mine. The only difference is that you don't have much margin for error.... with a 140 you can tell right away if the temp starts going up. On mine, if it gets up past 190 I know I have a problem but the window is a lot shorter to shut it down.

I agree, I run a 140 and has been doing great. With a higher temp (180) there would be little room for error. I also bought mine from the Auto Parts store, and I have the same housing that they shower earlier:

[Ptownkid]

Maybe I'll check somewhere else and go down to 170.

[Stal1026]

SIERRA MARINE-ONLINE-get the part number and go to the local NAPA store. Give them the part number and they can get it for you. Easiest way to order parts and then return if needed.

[TitanTn]

I don't think so. I run a 180 in mine. The only difference is that you don't have much margin for error.... with a 140 you can tell right away if the temp starts going up. On mine, if it gets up past 190 I know I have a problem but the window is a lot shorter to shut it down.

Good points. I should have said "I wouldn't run anything hotter..." I like having the margin where I'll know something isn't right before it gets even close to being damaging hot. Plus, it runs more efficiently at a cooler temp.

[Ptownkid]

I have always been told that they run more efficiently hotter...

[TitanTn]

I have always been told that they run more efficiently hotter...

They run better with some heat versus running them cold (no thermostat), but heat past a certain point does not help combustion. As long as you're within the temp range of that specific engine, you'll make more power on the cooler side.

[cadunkle]

180* is fine in fresh water, though I'd probably run a 160*. If salt or brackish you should be running a 140*-145* thermostat, anything hotter will react with the salt and cause problems with corrosion and plugging cooling passages.