Do I need 2 thermostats ?

[az79spider]

Looks like my 79 Spider has two thermostats, one in the head , the other in the "T" between rad hose and radiator. Do I need both, and if not, which one is best to keep. I dropped off my radiator at the rad shop. Only 1/5 of the cooling tubes were being utilized, the others were smashed thru. Its also a two row, like I assume all spider rads are, he's going to replace the entire tube section and see if he can make it 3 row. As long as its the same dimensions, that should help with cooling (I live in Az). Advise.

[TulsaSpider]

Definitely don't need two. There are differencing opinions on the subject. Perhaps the external stuck open and they added the in head? I think the consensus is that the external thermostat is the way to go. It's very important to get that radiator back into top shape and make sure your fan switch is functional.

[So Cal Mark]

one t-stat is plenty. Fiat went to the external stats as the motors got larger because the external stats flow more. As for the radiator, fin count is important too not just number of rows. The oem rads had a very high fin count while most recores do not have fin counts even close to the oem units

[baltobernie]

.... The oem rads had a very high fin count while most recores do not have fin counts even close to the oem units

I didn't know that, Mark. This may explain why some people fiddle with different fans, lower temp switches, etc. in an effort to make their cars run correctly. Even with more HP than stock, I've never had a problem with overheating, even when stuck in traffic with ambients above 95F. (I, on the other hand, overheated terribly ) Can you post macro photos illustrating OEM vs/ recore?

[az79spider]

do you have an estimation on oem fin count so i can get my rad somewhat close to that number ? I would "count" but my rad is at the shop. And we normally hit 115 degrees here in phoenix. so consensus is lose the head thermostat and keep the one between the hoses. will do.

[manoa matt]

The original rads were good because of the high fin count, in order to make the high fin count the fins were thin which means they easily clog up. I have a 3 row high efficiency re-core and it works great. Temps here are usually about 80 but it frequently gets in the mid 90's and traffic here is terrible. I use the stock fan and a stock 190F external thermostat, the fan switch is a low temp one 75C, the car running temp is around 185F and very very stable. The fan switches come in 95, 85 and 75 Celsius. 95 is considered stock, some vendors carry the 85 as a performance product. You can find a 75 deg. temp switch at a VW or European parts store.

[barnesjtsl]

Where is the thermostat in the head? I have a 79 and didn't know that there was a second thermostat other than the one between the radiator hose(s).

Do you have a picture?

jb

[az79spider]

no picture and the front end of motor torn out. I'm sorry, should have posted one. My rad will be getting that third row. Cost is 280. Sound reasonable ?

[Fiat88]

I'm having trouble with my fan not kicking on when it hits 190, lower rad hose stays cold. Just did the hole mod for my external stat also. I'm not 100% sure but there seems to be another thermostat in the head on my '79 also. Would this be the cause of my trouble? Any thoughts would be appreciated.

[courtenay]

Mark will sell you his larger aluminum rad kit for about $360 plus shipping. Check out his website.

[azruss]

When i went to redo my radiator, i took it down to a small shop in central phoenix. the guy said the tubes in the factory radiator are so small he didnt have small enough rods to ream them out and didnt think boiling them out would do an adequate job. I ended up buying an all new radiator from vicks and kept the old one for a backup. havent had enough road time to tell you how it works. I drilled my stat before i put it in and had no cold bottom hose issues.

[Fiat88]

Radiator is brand new from IAP!

[Fiat88]

Yes, I did have another thermostat in the head! I removed it. Why would I have 2 thermostats anyway?

The external thermostat is better right?