Anyone know how to make a 190F thermostat for a Series 1?
 

Yes, I searched. I specifically searched for "190F" and "195" and checked every thread that came up. Not one of them discussed what I am looking for.

The only thermostats available for the Series 1 seem to either be the OEM 180F or the aftermarket/competitive 160F. There does not seem to be anyone producing a 190F thermostat for the Series 1 RX-8.

My RX-8 has 85K miles on it and I've noted that the infamous hard starting when warm issue comes up if the engine doesn't run long enough at full operating temperature, and even with long drives, I usually have to throw a can of Seafoam in the tank once or twice each winter to free up whatever is getting stuck.

I am using Evans Waterless coolant and a BHR Radiator (I've also had a seized fan swapped out) so I am not particularly concerned about localized boiling in the coolant jackets near the exhaust ports, which is why I presume Mazda only offered a 180F thermostat (along with an apparent deficiency of extreme cold weather testing).

I recall that the FB RX-7 had thermostats available in 180F and 195F; but there does not seem to be a 190F or 195F thermostat on the market for the Series 1 RX-8. I am wondering if it is feasible to swap the core components from a 195F FB thermostat into the housing for an RX-8 thermostat in order to construct a viable 195F Series 1 RX-8 thermostat.

I'm trying to find comparable photos of the two designs to see if this is feasible or not; but it occurred to me that someone might know the answer already.

I don't understand, why do you think your hard starts are related to the thermostat?

There is also a 172F thermostat from Mazmart, but that obviously isn't what you are looking for.

What you are proposing should be viable.




I think your intent is flawed, your thermostat will have nothing to do with your hard starts when warm.

*facepalm*

So you're saying that because the car has trouble starting at temperature with the standard 180F thermostat, you want a higher threshold thermostat that will open later and let the engine get hotter. If the issue is related to heat, do you think the issue will get better or worse with more heat?

Also, get a compression test, this probably has little to nothing to do with the thermostat.

fixed

back to *facepalm mode*

Allow me to repeat myself, "...when warm issue comes up if the engine doesn't run long enough at full operating temperature, and even with long drives, I usually have to throw a can of Seafoam in the tank once or twice each winter to free up whatever is getting stuck"

The hard starts are related to carbon fouling of the apex seals, nothing more. When the weather gets cold, it's that much harder to achieve and maintain that temperature on drives of less than an hour. I've had this issue no less than four times, and dealt with it the same way, every time; but I would prefer to prevent it altogether.

The problem is due to insufficient temperature, as I explained above. Yes, I want a higher threshold thermostat. The car has trouble when warm, if and only if there is carbon fouling impeding the apex seals from sliding in their grooves. As I already mentioned, I've had this issue already had this issue at least four times, and I've addressed it, with difficulty, by prolonged drives of at least an hour. I've just finished burning off the carbon again, and the engine starts, when warm or cold, in the same three seconds that it took to start when I got the car in '04. What I want is to prevent this from happening any more. It's a pain. If you don't have anything better to contribute, just admit you're trolling and waste someone else's time.

Your engine is shot. and your logic is flawed.

*double facepalm*

I am pretty sure there is no thermostat with that temperature threshold for the 8 and I most certainly can not instruct you on how to construct one. Here is what you can do and it's a wee bit simpler than changing the thermostat each season. Get your self a nice piece of cardboard and block half of the radiator. This will effectively give you half of the normal cooling capacity. You will achieve the higher engine temperatures you desire. If you decide to go this route I HIGHLY recommend a coolant temperature gauge to monitor those temps. Too much heat and you fry the engine. You can try this and see how it works, I have a feeling something more may be wrong with your engine though.

longpath, they aren't trolling you (well, except the last guy that I edited).

The temperature of the coolant has nothing at all to do with the amount of carbon burn off, if that is indeed what you are trying to accomplish. A higher temp thermostat will only mean that the coolant's target temp is another few degrees higher. If will still reach 172F in the same time as a 172F or 185F thermostat. You will just be letting it go a bit higher.

The ONLY way that running with 190F coolant instead of 185F or 172F coolant will impact hot starts is that you will be running the block slightly hotter, meaning slightly LESS compression, since this engine generates more compression when cold than when hot. If anything, running at 172F will reduce the hot start problem ever so slightly. The difference won't really be noticeable however.


If you want to try a 190F thermostat, by all means try it. But it isn't going to solve your problem, and is taking away some of the buffer zone between you and more severe problems.

^ Exactly.

You would be better off running hotter plugs, especially if your car is used mainly for around town driving. Hotter plugs will at least give you a chance of burning fuel better and not building up carbon if you live in a cold area of the country.
Instead of running 7's and 9's, try running 6's and 7's. Finding the plugs might be the hard part though.

Rotaman

NGK sells the 6 plug for 8 for a short while, but I guess Mazda stopped it and those are NLA in the public, the only way to get 6 plugs is from Mazda now.

but in his case ... *facepalm*

Carbon doesn't accumulate as quickly as you think it does. Your car hard starts after warming up for a bit because your engine has low compression. That is all. Ask me how I know.

The carbon accumulation is seasonal. Are you suggesting that it takes more than a month to month and a half? I am not suggesting that the carbon accumulation is building up from a single run of the engine. It occurs every winter, and I am quite tired of it. It coincides, every winter, with heavy condensation in the oil.

Once the weather warms up, any starting issues I have in winter goes away. I don't have the issue all summer. I've seen this cycle going on for at least six years now. Once it clears up, the engine starts, even when warm, in 3 seconds. If the engine was shot, as several of you suggest, please explain how my engine is magically rebuilds itself once the weather warms up.

I'll try to make this simple

In warm weather:
No condensation in the oil.
No hard starts when warm.

In cold weather:
Lots of condensation in the oil.
After a couple of months of cold and damp, hard starts when warm.

This is cyclical and has been going on no less than six years.

I appreciate the lead on hotter plugs! Thanks for that!

You're assuming that I want to treat the symptom instead of treating the root cause. The root cause is seasonal carbon build up, during winter. It responds to decarboning procedures such as Seafoaming. I am not looking for an increase of temperature to tighten or loosen the block. If I was, I would install a 160F thermostat. I am looking to burn off carbon in normal operation in order to prevent the root cause of the temporary loss of compression. If this loss of compression was not due to carbon build up, then it would not respond to decarboning; but, in my case, it absolutely does. I am not looking to correct symptoms.

I have spent the last six years looking at this cyclical issue. When it first came up some six years ago, I thought I was going to have to have the engine rebuilt and just as I was getting an appointment for a compression test, the weather warmed up enough and all the symptoms went away.

Would you have a compression test on an engine that starts on the first try, every time, cold start or hot start, for nine months out of the year or would you try to figure out why cold weather screws it up?

Do you add seafoam to your fuel? If this thermostat idea doesn't work out, it could end up being your proverbial "ounce of prevention." Also, a desiccant breather for your oil sump may help prevent some of the water from making its way to your sump.:dunno:

Understood on the seasonal, bit, that wasn't clear at first. I saw something similar while I was living in RI too.


I still don't believe that running 5 degrees hotter coolant temps will produce any effect on carbon accumulation in the winter. The combustion temps will still be just as hot as before, that that is what has the impact on the carbon.

A better battery and a 2009-2011 RX-8 starter upgrade. Messing with the thermostat will do nothing at all.

I think everyone is attacking a red herring in this. The true culprit is winter blend gasoline obviously. OP's efforts would be better served purchasing a 1000 gallon container and filling it with gasoline during the summer for use in the winter.

Seafome in the gas? I thought that was a realy bad thing to do. The sea fome is washing the protective layer of oil from the apex seals all the time this would increase the apex seal wear at a massive rate. And you think running the engine hoter is good to? Sea fome in the gas + hoter running temp could only = dead engine.

Edit
Forgot to be helpfull. I have the same problem on a realy cold day you just need starter and mainly battery upgrade I would suggest a dry cell battery as this is what I use and it holds out better to the 8s power demands than all the other battery's I've had

I think the OP should not be surprised to get a comp test with failing numbers, out of all the 8's that drive year round in the winter. I have not heard of one die from carbon build up, without low compression first. The combustion chamber burns at up to 2000 degree's, increasing your nominal coolant temp 5-10 degrees is not going to change anything.

Stop putting a band-aid on your car and get it properly diagnosed.

I agree with that much. Heat is the enemy.

One the other hand, Seafoam is not. Could it be contributing to delaminating oils from the rotor casings? Sure, but so is the normal combustion process. Lots of guys use it to clean fuel systems, and it would be difficult to prove that it has increased the failure rate of affected rotary engines. I'm not sure about frequency for the OP's case. I usually go with "when I notice the car running a little rough."