Thermostat 440

LJ-TJ · June 04, 2019, 07:58 AM

Hey guy's, Having an over heating problem. Does the 1975 M300 take a skirted thermostat. i?? Thanks

BamBam · June 04, 2019, 01:01 PM

I don't even know or heard of a skirted T-stat? i?? i?? i?? Just stick with the standard 180* stat that all Mopars use. Why are you overheating? Good Luck

LJ-TJ · June 04, 2019, 05:06 PM

D:oH! That's what I'd like to know. Just got the rad re cord for $1000.00. Just put in a new water pump,clutch fan and thermostat. Fire here up and boom right up to 210. I pulled the thermostat and am going to fire here up later and see what happens. Hm?

ClydesdaleKevin · June 04, 2019, 07:01 PM

I am 99% sure that 440s use a skirted thermostat, just like 413s.

Kev

BamBam · June 04, 2019, 07:30 PM

This is what you want, even though it's for a charger. How much you want to spend? Just make sure that it's a 180* stat. Good Luck
https://www.napaonline.com/en/search?text=thermostat&referer=herofitmentForm-newveh

DaveVA78Chieftain · June 04, 2019, 10:07 PM

Yes the 440-3 uses a skirted thermostat.

1. Select the Dodge forum
2. Select Most commonly asked questions
3. Select Thermostat: Sources for a 440-3 thermostat

The Mr. Gasket one (4367) is the most common one found.

LJ-TJ · June 04, 2019, 10:24 PM

Thanks Dave. That's what I thought and bought. I always like to check with you guys just in case I missed something.This things go me buffaloed. Shoot! Re-cord the rad, new thermostat, new water pump,belts are good, hoses are good. Got me. Really appreciate all your help over the years. Thanks Mate.

Elandan2 · June 05, 2019, 08:35 AM

Gauge sensor?

Rickf1985 · June 05, 2019, 08:38 AM

Head gasket blown? Is it building up pressure in the radiator quickly and blowing over.

LJ-TJ · June 05, 2019, 09:53 AM

Ok! So I'm loosing my mind here. I pulled the thermostat this morning and let the old girl idle for 1hr, Yep! an hour. the temp never went above 135. So I check under neath on the block and it says it's a 440-10 D:oH! On the left side of the block by the water pump it has J440 TX with a iron cross. Blow that it has 7 a space with now writing and then a 20. I got no idea. I'm totally lost. What flipping engine do I have. Do I need a skirted thermostat or a regular thermostat.

Sorry for being such a pain in the !@#$%^&*()_+

BamBam · June 05, 2019, 12:48 PM

Quote from: LJ-TJ on June 05, 2019, 09:53 AM
Ok! So I'm loosing my mind here. I pulled the thermostat this morning and let the old girl idle for 1hr, Yep! an hour. the temp never went above 135. So I check under neath on the block and it says it's a 440-10 D:oH! On the left side of the block by the water pump it has J440 TX with a iron cross. Blow that it has 7 a space with now writing and then a 20. I got no idea. I'm totally lost. What flipping engine do I have. Do I need a skirted thermostat or a regular thermostat.
Sorry for being such a pain in the !@#$%^&*()_+

With that being said, I would say you have a stat problem. As for the markings on the block, all I know is the cross means that your bearings are .10 under. Compare the stat you have with a new one. The links in this topic are confusing, the last post here, http://www.classicwinnebagos.com/forum/index.php/topic,2629.0.html sends you to this link. https://www.performanceparts.com/mr_gasket_thermostat_4367
If you read what that says about what it's for raises a flag!
"For High Performance Street, Drag Race, and Oval Track"
I think your making this to hard on yourself! Compare stats and replace with the same! This ain't rocket science unless you want it to be!

Rickf1985 · June 05, 2019, 02:10 PM

This may be a dumb question but did you have the thermostat in the correct direction? With the sensor bulb towards the engine.

DaveVA78Chieftain · June 05, 2019, 02:30 PM

QuoteSo I check under neath on the block and it says it's a 440-10

The -10 just represents the casting number, not the 440 type.

QuoteOn the left side of the block by the water pump it has J440 TX plus irn cross

J = Plant where the engine was built (not sure what it decodes to)
440 = displacement
T = Truck engine which was the 440-3 version
X plus iron cross = 0.010 undersize crankshat bearings

You have a 440-3
If you look at the Dodge MH Service Manual, Group 07 - Cooling System, Page 7-7, Figure 7, you will see a picture of the skirted thermostat used on the 440-3 truck engine. A 440-3 truck engine used in motorhomes and vans is not made the same as the 440-1 car engine which us why you have to use a skirted thermostat which allows proper water flow through the engine.

LJ-TJ · June 05, 2019, 03:14 PM

Thanks guys, Dave, Rick and Bam. I have the skirted thermostat. I put it in a pot of hot water with a thermometer. I opened at 177dg and fully opened at 185. So heading out to re drain the rad and install it and see what happens. Good question Rick I put the pointy end up into the rad hose and the fat end into the water pump. Think that's right. Thanks guys.

Elandan2 · June 05, 2019, 04:21 PM

Sounds like you may have had an air pocket behind the thermostat. I like the ones with a "jiggle" valve in them to eliminate that problem. In vehicles where I've had a problem with air stuck behind the thermostat, I drill a small 1/16" hole in the flange and that lets the air out but doesn't affect performance.

cosmic · June 05, 2019, 04:24 PM

I too use that trick.. 1/16 hole just off to the side.
TJ I had to start mine run it until it got hot turn it off let it cool repeat 3 times till I finally got that damn air lock out.