Thermostat thread

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RobertH6657

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k-rub. I have tried to put on the SPD 170 and i found the stock thermostat is indeed 195F and the overall height of it to be 61mm. The SPD 170 stat is 64mm in height. While 3mm does not sound like much (it's about 1/8"), I found the SPD stat not only hitting the back of the water housing and literally you have to press the stat in compressing the spring about 2mm in order to put the thermostat housing back on. That means (i think) that the stat sits firmly in compression on the bypass of the radiator. The stock one doesn't touch at all. My concern is that when the stat heats up, it moves backwards to hit the bypass and then the stat opens. Did your stat hit the back of the housing and did you have to slightly compress the springs to get the stat to install? This doesn't seem right to me. Your feedback is appreciated.
 

RobertH6657

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So after three calls to three different 170F thermostat providers, they ALL are 64mm tall. Your stock stat is 61mm. There is a challenge when you swap them out because you literally have to compress the spring in the 170F stat while you are putting the plastic water housing back together and align the stat so you don't pinch the O-rin gasket. What a pain in the ass!! The stat (which I put the original Factory O-ring gasket on the 170F stat because it is substantially larger and seals better) will NOT sit in place while you reassemble. The spring pushes the stat out the moment you let it go when trying to put the housing back on. When that happens, the stat falls down and the housing pinches the O-ring and there is no way to put the housing on because you can't manipulate the stat. So here's what I did, which WAS successful. First, I lubricated the outside rim of the stock O-ring with Magic Lube (pool o-ring lube) so it would slide easier into place. I think that lube was the key to success BTW. Secondly, I removed the 3 factory 8mm screws and tossed them aside. I then went to Ace Hardware and bought and installed three Metric 9mm 2" long all-thread studs. Screwed them in by hand (key word is by hand) about halfway approx 1", leaving 1" remaining stud sticking out, no problem. Then I slid the housing onto the three studs and of course the stat was popped out falling down, resisting me from tightening the housing down. Then I put washers and nuts on the three studs using my fingers only, no tools, and put them on as far as i could using fingers only. Then i stood on a ladder and reached around on both sides of the housing and shook the housing vigorously while pushing the housing on. It took a few tries, but the studs lined everything up, and the Magic Lube somehow allowed the o-ring to squeeze into place and put the spring under compression while I felt the housing move into place. Once I felt the housing hit the flange, I used my fingers to spin the nuts on further while I kept pushing until the housing was in place. Then I used a socket wrench to tighten them down evenly. What a complete and utter pain in that ass. If SPD, Reisch and Ratstat could just make a 170F stat 61mm in height (like the stock one) instead of 64mm in height, this would be a 5 min job....OMG!!! They must make them taller so they can fit them in multiple vehicles. Hopefully, this will help some of you if you try to DIY. Final advice...Do NOT try to reuse your existing three bolts, one of the three will try to cross thread on you during reassembly. Get the studs. That was also key to line up everything. A new Intercooler is next on the agenda.
 

Booth9999

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k-rub. I have tried to put on the SPD 170 and i found the stock thermostat is indeed 195F and the overall height of it to be 61mm. The SPD 170 stat is 64mm in height. While 3mm does not sound like much (it's about 1/8"), I found the SPD stat not only hitting the back of the water housing and literally you have to press the stat in compressing the spring about 2mm in order to put the thermostat housing back on. That means (i think) that the stat sits firmly in compression on the bypass of the radiator. The stock one doesn't touch at all. My concern is that when the stat heats up, it moves backwards to hit the bypass and then the stat opens. Did your stat hit the back of the housing and did you have to slightly compress the springs to get the stat to install? This doesn't seem right to me. Your feedback is appreciated.
Something seems wrong here.. will the stat still function correctly?
 

RobertH6657

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The stat works fine, just getting it on is painful. It only compresses about 2-3mm but it's pushing up against the bypass which according to Reische is fine. I went to MPT and they verified that everyone is experiencing the difficulty of installation issue. Here's why it is in fact an issue. Your stock stat is 61mm in height (it is clearly stamped on he stat). These three aftermarket 170F stats are also clearly stamped with 64mm. The 61mm stock unit is designed so that it will sit in place during reassembly (which makes sense) and it just barely touches the back of plastic water housing against the bypass. If there was any more clearance, the bypass would not work correctly during engine warmups. The extra 3mm DOES hit the back of the housing leaving 3mm of the stat sticking out and it doesn't sit in place. If you try to push it in place (there is a groove cut in the water housing to hold the stat in place while reassembling) the spring on the brass side of the stat pushes it out during reassembly. The main valve spring that opens the stat for radiator fluid to flow is NOT the spring under compression during reassembly. It is the opposite side. The brass side. I called Reische and they told me that the little bit of compression is OK as they want to stat to sit firmly against the bypass. They said that it will not hurt a thing. It's just painful to install.
 

zemuron99

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If SPD, Reisch and Ratstat could just make a 170F stat 61mm in height (like the stock one) instead of 64mm in height, this would be a 5 min job....OMG!!!

Pics? It seems like it would be more complicated than '5 minutes', with the air intake tubes, radiator hose routing, etc. But...maybe I'm over-analyzing this. I haven't found a good video/pic essay on doing this on the 3.5 L Ecoboost. I put a cooler t'stat in my Tacoma when I put the TRD supercharger on, and nearly never get knocking, even when on trails. Would like to see my E-boost 10-15 degrees cooler as well. Or if you know where a good write up with pics (or vid is) and can share the link(s)...
 

dewalt

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By my way of thinking thermostat should open ,shutters open, and the fans come on. Fans come on at 190-195. My 170 runs 190 degrees most times . Never seen it over 200
 

nikhsub1

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By my way of thinking thermostat should open ,shutters open, and the fans come on. Fans come on at 190-195. My 170 runs 190 degrees most times . Never seen it over 200
If your truck is tuned you can have your tuner program the fans to come on sooner then they normally do. I think mine kick on around 185F or 180.
 

zhengyucoo

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I ended up with 180 stat, I think 170 is too low for me. My truck is running at 190-210 (local-highway)
 

dewalt

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There is a difference in stats. Some seem to be on- off and some have a range. IE the range from open to close is different. Haven't found that in specs , but seems like how it works
 
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