Cosworth coolant temperature
 

I searched and didn't find an answer. My question is for anyone running a Cosworth low temperature thermostat or any other low temperature thermostat. What coolant temperatures are you seeing? I expect the engine to run cooler in the wintertime but it seems like it's running too cool. I ran Toyota Techstream to see what the actual coolant temperature was. It was reading between 142F to 147F. According to Cosworth, the thermostat is not supposed to start opening until 169F. Engine running temperature is supposed to be 176-180F. Think maybe I just didn't purge the system good enough or is this the nature of the beast?

I had been running a little easy since replacing the thermostat last weekend. Today I got into it and ran up to redline and the coolant temp climbed up a little and stayed there. Even after settling down and cruising at 2000 rpm, the coolant stayed up higher than where it was previously. This makes me think that the thermostat might not be stuck open because it would have dropped back down again once I let off the throttle. I think it's possible there could still be a little air in the system. I haven't seen the reservoir drop though so if there is any air in there, it seems to be very little. Ideas? Or is this how a low temperature thermostat operates? Opening sooner... I know. But letting it run this cool?

Thanks.

I seriously doubt Cosworth designed the system to run this cold. I don't think it's even going into closed loop mode. My mileage has dropped from 36 to 32mpg. If I turn the heating controls to AUTO, it never ramps up the fan speed, instead staying on low. This also indicates that the ECU thinks the system is too cold.

So this weekend I'm going to take the thermostat out again and see if either I put it in wrong or if it's stuck open. Maybe it's not completely centered in the housing or maybe I pinched the spring open when trying to work around the dang exhaust. I'll let you know how it works and what coolant temps I get.

Good plan!

I would guess the thermostat is never closing.

Either it's bad or you put it in backwards.

Back in the day, we used to put a thermostat in a pan of water on the stove and fire up the heat (checking with a candy thermometer) to see if/when it would open ......:popcorn:


humfrz

Well I found what the problem is. Cosworth sent me the wrong thermostat. The one I have starts opening around 140F and by 155F it's open. The picture of the BRZ thermostat doesn't match the one I have either. Mine has 2 springs and a rounded top.

It's a Mitsubishi EVO thermostat. They open at 155F :mad0260:

Now to put the OEM stat back in and wait for Cosworth to send me the right one from England.

[edit] I ended up parking the car until I receive the correct thermostat. It's such a pain to replace and I don't want to do it twice.

At least they're sending you the right one.

It's now been over 2 weeks. I still don't have a running car. I contacted Cosworth and explained to them that the car was never getting up to temperature. Correspondence is very slow. If you are going to contact them, call them. Email typically takes 1-3 full days for them to get back to you.

I think I have the wrong thermostat. Cosworth explained that there should be a stamp on the thermostat indicating the opening temperature. Mine has no markings whatsoever. I sent them detailed pictures of the thermostat I have. A week later, after still saying nothing, I called them. I told James at Cosworth that I still don't have a running car. He then said that they would be shipping me a replacement out that day. Now a week after that, I still don't have a thermostat.



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The thermostat I have was packaged with the correct part number on the label. But I know for a fact that it is not opening where it is supposed to. In as little as 120F it starts opening. My car never heats up and stays in open loop mode. Before I knew all this I nearly tore the transmission out of my car playing around with flat foot shifting. Apparently these features are disabled if the car is not up to temperature (not mentioned in any literature). When I floored it and pressed in the clutch, the car reved to 8000rpm and then the transmission grinded the gears getting back in.

Have you tried contacting Matt@Cosworth here on the forums? He's active on the Cosworth Supercharger Owners thread.
http://www.ft86club.com/forums/showt...=94403&page=21

I realize you don't have the kit, but he is on the forums and is generally quick to respond. I'd say see what he can do to help. I can't recall if my thermostat said anything on it tbh haha. Again, hopefully you can be fine.
Also... I ran my Cosworth 1.2 tune without the thermostat (only the exhaust pieces, intake filter, and tune) for a couple months with 0 problems till I installed my supercharger.

Thanks. I'll try to get in contact with him. Just feeling frustrated. I miss my car. I may go ahead and put the OEM back in if the replacement doesn't arrive soon. I worry about spark knock with the Cosworth tune and the OEM thermostat. However I have read that many people on here have run OEM without problems.

That's what knock correction learning and ignition advance multiplier are for.

You'll be fine.

I would cut my losses and buy a replacement Cosworth thermostat from rallysportdirect, send cosworth the bill.

You'll never get paid, but at least you'll have the car and an excuse to be mad.

+1

many apologies for this
I'd agree that the quickest way to get a thermostat is to get in touch with Rallysport they will then bill us for a replacement
I'm assuming that you purchased the kit not through RSD so as the aftermarket arrangement has since changed you can't go back to the place you originally purchased it from ?

Thanks for responding. Just venting a little... I purchased the stage 1.0 online from Speedzone Performance. I called them at the beginning of this and explained to them about the thermostat. They said that there is nothing they can do and to contact Cosworth. I spoke with James and while he has been very helpful and friendly, I still don't have a thermostat. I was told that it was shipped but so far nothing has arrived. I don't have a tracking number but I'm sure those are not available for international shipments.

I asked James if they wanted me to ship my current thermostat to them but he said to just keep it. I can place an order for one through RSD but I'd hate to do that and then the next day one from Cosworth shows up. I guess I don't know know if I should just keep waiting or to go ahead and order one.

I say go ahead and order it. Worst case scenario is you have a spare to sell.

Done. I went ahead and ordered one from RSD. If the one from Cosworth ever shows up, I guess I'll just list it on eBay.