Thermostat 351M/351W
#1
12-19-2015, 02:26 AM
#2
12-19-2015, 09:12 AM
The351C/M/400 takes a special thermostat with a kind of collar around it. A 192-5°F thermostat is the one to use. Use only the Cooper-Robertshaw thermostat. This has been discussed many times inthe 335 series engine forum.
Whereto buy a 335 Series thermostat
3options:
-Finda dealer with a RT-139 still in stock.
-Robert Shaw 333-180
-Napa THM297
Dealer in Kansas they will ship itto you. Bob Allen Ford 1(800)676-0675
Whereto buy a 335 Series thermostat
3options:
-Finda dealer with a RT-139 still in stock.
-Robert Shaw 333-180
-Napa THM297
Dealer in Kansas they will ship itto you. Bob Allen Ford 1(800)676-0675
#3
12-19-2015, 12:15 PM
Lead Driver
I've always used the Robert Shaw 333-195 and never had a problem since learning the lesson back in the '80s when I installed a new T-stat and coolant and noticed that my engine would steadily continue to heat up when it hadn't before. That was when I ordered a Flowkooler water pump kit and they sent a Robert Shaw 333-195 T-stat with it. The Flowkooler WP kit added a stainless steel disc to the back side of the water pump impeller to hold the coolant on the vanes and prevent cavitation She never get's hot since, just heats up to 190-192 on the mechanical gage and sits there like a rock, regardless the load or speed.
Like said above ..... and I know it's tempting to toss in the wrong one ..... but that collar ("hat") that is part of a 351M / 400 T-stat is there to slowly restrict the bypass passage in the block that runs into water pump .... restrict it as the T-stat opens to force coolant to the radiator instead of being sucked back into water pump to be recycled back through the engine .... which will lead to a slowly skyrocketing temperature gage. The first pic below is a page explaining the cooling on a 351C .... which was the first 335 series engine. Later came the 400 and then, the 351M based on the 400 block. All three share the need for this same T-stat.
I have read it several times that if one has an old Robert Shaw 333-180 or 333-195 they wish to replace, that the 330 series is the same T-stat but without that "hat" on the bottom. I've read of folks carefully removing the hat off the old 333-xxx and pressing it to same position on the 330-xxx T-stat.
I've also got a link on Ebay for the correct 351C / 351M / 400 T-stats .... 351C Robertshaw Thermostat 180F Degree The Correct One with Copper Skirt 351C | eBay or 351C Robertshaw Thermostat 195F Degree The Correct One with Copper Skirt 351C | eBay
The listing claims it will not fit anything but a 351C ..... but the 351C and 351M and 400 all take the same T-stat. Only the 351C takes the plate in the block below the T-stat. I sent him a question on this point and he gave a good reason for his wording, it has to do with a customer complaint whom had a 351W ..... and since his primary interest is Panteras ..... he changed the wording .... but YES ..... these T-stats will fit the 351M & 400 perfectly, just don't need the restrictor plate in the block. I see the description has been changed accordingly.
Like said above ..... and I know it's tempting to toss in the wrong one ..... but that collar ("hat") that is part of a 351M / 400 T-stat is there to slowly restrict the bypass passage in the block that runs into water pump .... restrict it as the T-stat opens to force coolant to the radiator instead of being sucked back into water pump to be recycled back through the engine .... which will lead to a slowly skyrocketing temperature gage. The first pic below is a page explaining the cooling on a 351C .... which was the first 335 series engine. Later came the 400 and then, the 351M based on the 400 block. All three share the need for this same T-stat.
I have read it several times that if one has an old Robert Shaw 333-180 or 333-195 they wish to replace, that the 330 series is the same T-stat but without that "hat" on the bottom. I've read of folks carefully removing the hat off the old 333-xxx and pressing it to same position on the 330-xxx T-stat.
I've also got a link on Ebay for the correct 351C / 351M / 400 T-stats .... 351C Robertshaw Thermostat 180F Degree The Correct One with Copper Skirt 351C | eBay or 351C Robertshaw Thermostat 195F Degree The Correct One with Copper Skirt 351C | eBay
The listing claims it will not fit anything but a 351C ..... but the 351C and 351M and 400 all take the same T-stat. Only the 351C takes the plate in the block below the T-stat. I sent him a question on this point and he gave a good reason for his wording, it has to do with a customer complaint whom had a 351W ..... and since his primary interest is Panteras ..... he changed the wording .... but YES ..... these T-stats will fit the 351M & 400 perfectly, just don't need the restrictor plate in the block. I see the description has been changed accordingly.
#4
03-17-2017, 08:36 AM
I've always used the Robert Shaw 333-195 and never had a problem since learning the lesson back in the '80s when I installed a new T-stat and coolant and noticed that my engine would steadily continue to heat up when it hadn't before. That was when I ordered a Flowkooler water pump kit and they sent a Robert Shaw 333-195 T-stat with it. The Flowkooler WP kit added a stainless steel disc to the back side of the water pump impeller to hold the coolant on the vanes and prevent cavitation She never get's hot since, just heats up to 190-192 on the mechanical gage and sits there like a rock, regardless the load or speed.
Like said above ..... and I know it's tempting to toss in the wrong one ..... but that collar ("hat") that is part of a 351M / 400 T-stat is there to slowly restrict the bypass passage in the block that runs into water pump .... restrict it as the T-stat opens to force coolant to the radiator instead of being sucked back into water pump to be recycled back through the engine .... which will lead to a slowly skyrocketing temperature gage. The first pic below is a page explaining the cooling on a 351C .... which was the first 335 series engine. Later came the 400 and then, the 351M based on the 400 block. All three share the need for this same T-stat.
I have read it several times that if one has an old Robert Shaw 333-180 or 333-195 they wish to replace, that the 330 series is the same T-stat but without that "hat" on the bottom. I've read of folks carefully removing the hat off the old 333-xxx and pressing it to same position on the 330-xxx T-stat.
I've also got a link on Ebay for the correct 351C / 351M / 400 T-stats .... 351C Robertshaw Thermostat 180F Degree The Correct One with Copper Skirt 351C eBay or 351C Robertshaw Thermostat 195F Degree The Correct One with Copper Skirt 351C eBay
The listing claims it will not fit anything but a 351C ..... but the 351C and 351M and 400 all take the same T-stat. Only the 351C takes the plate in the block below the T-stat. I sent him a question on this point and he gave a good reason for his wording, it has to do with a customer complaint whom had a 351W ..... and since his primary interest is Panteras ..... he changed the wording .... but YES ..... these T-stats will fit the 351M & 400 perfectly, just don't need the restrictor plate in the block. I see the description has been changed accordingly.
Like said above ..... and I know it's tempting to toss in the wrong one ..... but that collar ("hat") that is part of a 351M / 400 T-stat is there to slowly restrict the bypass passage in the block that runs into water pump .... restrict it as the T-stat opens to force coolant to the radiator instead of being sucked back into water pump to be recycled back through the engine .... which will lead to a slowly skyrocketing temperature gage. The first pic below is a page explaining the cooling on a 351C .... which was the first 335 series engine. Later came the 400 and then, the 351M based on the 400 block. All three share the need for this same T-stat.
I have read it several times that if one has an old Robert Shaw 333-180 or 333-195 they wish to replace, that the 330 series is the same T-stat but without that "hat" on the bottom. I've read of folks carefully removing the hat off the old 333-xxx and pressing it to same position on the 330-xxx T-stat.
I've also got a link on Ebay for the correct 351C / 351M / 400 T-stats .... 351C Robertshaw Thermostat 180F Degree The Correct One with Copper Skirt 351C eBay or 351C Robertshaw Thermostat 195F Degree The Correct One with Copper Skirt 351C eBay
The listing claims it will not fit anything but a 351C ..... but the 351C and 351M and 400 all take the same T-stat. Only the 351C takes the plate in the block below the T-stat. I sent him a question on this point and he gave a good reason for his wording, it has to do with a customer complaint whom had a 351W ..... and since his primary interest is Panteras ..... he changed the wording .... but YES ..... these T-stats will fit the 351M & 400 perfectly, just don't need the restrictor plate in the block. I see the description has been changed accordingly.
This should be a sticky if it's not already. Thank you!
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