MSM cooling issues
 

Alright guys, been digging around various forums to address cooling on my MSM after seeing the car hitting 220f idiling the other day. As i understand, this is normal-ish in hot weather with the AC on, but makes me a bit uneasy. Emilio's cooling thread was quite helpful, but i am still trying to get a bit of info as it pertains to the MSM and specifically radiator fitment with the stock MSM fan/fan shroud, charge piping and AC condensor. Three options I'm exploring:

1. Stock Radiator - the PO replaced the radiator with another MSM radiator just before i bought it so it's pristine. Foam strips still in place on all 4 sides and undertray is still there. Evidently, FM tested the OEM MSM radiator and it outperforms basically everything except their crossflow radiator. Car is running a 50/50 coolant mix, which isn't ideal. Thinking distilled water with water wetter and a splash of coolant to keep the WP happy and to make it easier to find leaks an see how that works.
2. CSF dual core - Emailed supermiata about this and got some good info. What i can't quite figure out is what needs to be "tweaked". Did some digging around and found a few older threads that the fan shroud needs to be trimmed and AC condensor adjusted a bit but these are 5+ year old threads. Any MSM owners with stock charge piping recently gone down the this rabbit hole?
3. Supermiata Crossflow - MSM facebook group has a few guys who say this will work by simply sliding the condenser up, but supermiata told me this would entail a bit more than that (custom charge pipes and either major ac work or a delete). I'd lean towards trusting supermiata since they're the foremost experts here vs. random guys on a facebook group. Any MSM owners on stock charge piping gone down this route?

Trying to get my bearings here a bit specifically with the MSM's oddities. Going to try option 1 this weekend just and see if i get a little improvement there but also thinking long term here. The car is primarily a street car, but i do have plans to see some track time here and there with the car and want to keep the car cool and looking for the option that requires the least amount of hacking ideally. Feedback, experience, and bad jokes/cat pics all welcome. Thanks.

The MSM forum is now closed but is still readable and contains useful MSM-specific information so do some digging there: Mazda-speed.com - Index
Some of this information has been transferred to miata.net.

50/50 coolant mix is insane so flush it and replace with recommended mix.
The MSM radiator on an unmodified MSM should be more than sufficient - if it's in good condition, keep it!

I'd also recommend upgrading the token MSM-intercooler, on a hot day at the track or highway it heat-soaks quickly and is useless.
An e-BAY intercooler is sufficient for even a lightly modified MSM.
The MSM OEM intercooler plumbing uses steel pipes which rust badly on the inside. By now they will probably be flaking rust so you're risking getting them sucked into your engine.
If you haven't done so already, pull them out and give them a thorough workout with a wire brush or replace them altogether with aluminium or stainless pipes.

Thanks, I did some digging around there as well, which is where i found the info on the various slight fitment issues using the CSF radiator. Those threads were all from 2013 or so, so not sure if the design of the radiator has changed any since then (hence this thread). The OEM IC pipes on mine are mint actually. It's been a south FL car it's whole life, so not a single speck of rust on anything (a sight to see on an NB these days lol)

Should have also been more clear as well, I'm slightly modded (FM intake, DP, exhaust, ebay intercooler AKA the little enchilada). Going to try option 1 i mentioned above as I'm sure it'll help, but long-term is to replace the radiator all together with something more robust, hence this thread to get an idea of what fits plug and play with OEM fans/shroud and IC piping and what will require tweaking.

Any other MSM owners have some insight? About to break google from all the permutations i keep trying to get information lol.

My MSM is about as modded as a stock engine & stock turbo setup will go, 3" turbo back, ebay IC, custom turbo intake pipe, megasquirt, flex fuel, etc. I daily drive it and I live in Queensland Australia where it's currently summer and it gets hot. I run the stock radiator (replaced original with new OEM ~4 years ago), I have the under tray, and a diverter panel on top of the rad. Nothing special. I have no issues at all. Car handles crappy traffic without issue, gets up to about 97*C (~206*F), then the fan brings it back down to 92*C (~198*F).

The transmission tunnel gets hot, and the AC has a hard fight on it's hands to keep the cabin even slightly cool. But that's the price of 3" stainless running so close to the sheet metal. The engine is in a very happy and safe operating temperature window.

Good to know. I'm going to flush the coolant and go with an 80.20 mix next week and then pull the bumper off and start seeing what I can do in terms of ducting. Also realizing most radiators would require a bit of finagling with the MSM's fan shroud/ and cold side piping, so i'm fairly certain i'll be going down the CSF radiator route in short order.

https://cimg4.ibsrv.net/gimg/www.mia...aa7a4fc235.jpg
I used the supermiata crossflow in my msm. Stock fan shroud trimmed around the radiator necks, believe that was it. Upper hose can be trimmed to improve tight clearance, but it's not a problem or use 2-pc hose & hosegina like i did. IC tube bracket has to be unbolted and either bent or cut to allow fitment due to the fill neck which protrudes out and located at the end of the end tank.

Yes, when I looked at the air paths around (as opposed to through) the radiator, I was appalled. Far too many big opportunities for air to take the path of least resistance. This was a concern as I have removed the twin fans, and replaced them with a single fan, and an oil cooler in place of the second - I need all the air entering the mouth to pass through the radiator. I have now put a lot of effort into the ducting and am pretty confident that even if it is not all perfectly sealed, it is a damn sight better than it was. However, the car is still on jack stands and I can't be sure until it has been run hard. Some pictures here https://www.miataturbo.net/prefabbed...e-94572/page2/

This is the kind of feedback I was looking for. Thanks!

I heard of some issues with the supermiata crossflow in the MSM, namely needing custom IC pipes (presumably due to the hot side piping hitting the fill neck?) and some issues with the AC condenser. The crossflow would easily be my first choice if i can make it fit. Aside from what you mentioned about trimming the shroud, the upper house fitment and the hot side piping, any other issues you run into?

Good info on your thread. Thanks for sharing. Going to dig into this a bit as well in the next week. Flushed the coolant and went straight distilled water, a splash of coolant and some water wetter and that's helped, but since I do plan to see track time with the car to some degree, i want to make sure the car is bulletproof cooling-wise.

Good stuff. Got my supermiata crossflow fan in car today. Had to move the AC condenser in front of the mounts,easy. That gave plenty of room for the rad. I'm still undecided on the fans. I trimmed the stock shroud and it fits fine. Just dont know if it will be up to the task of a street driven 300 hp car with AC.

https://cimg9.ibsrv.net/gimg/www.mia...97aed850d9.jpg
https://cimg0.ibsrv.net/gimg/www.mia...6f814e72e8.jpg
https://cimg1.ibsrv.net/gimg/www.mia...8f199ed529.jpg

If you do all the other stuff; reroute, ducting, sealing, hood vents.. yes.

Just to update, the car is still running hot in stop and go traffic in 90+ degree weather. Car hit 225f the other day cruising around town, but going distilled water/splash of coolant and water wetter has helped a bit when driving around. Car holds temp nicely at 195-205f at anything over 30mph or so, so i'm clearly dealing with an airflow problem here. Fans appear to be working fine. MSM fans are weird, but they're effectively 2 speed fans that hit low speed at 206f and high speed at 221-222f. Both "modes" work fine from what I can see.

Any benefit to be had from swapping radiators to something with more capacity, or should i be running right to a set of fans and some ducting? Thinking of the CSF rad as a fair option for a "dual duty" street/occasional track car and FM's fan kit. Really wish the 949's crossflow fit but it seems like there's a bit of finagling there to make it fit that i'd rather not have to do.

I may have missed it… do you have a re-route? That is step 1.

No reroute. That's another thing i just started researching this morning. Seems "internet lore" is no reroute on the MSM unless you swap to the 94-00 HG but now starting to go down that research rabbit hole now that you mention it.

@emilio700 says Reroute Period, Period, Period. Swapping head gasket is preferred, but not necessary. Still should reroute.

Otherwise, I can say that reroute on my '99 was the biggest single item to tame A/C related CLT problem.

You will find that the forum leaders here do not subscribe much to internet lore ;) There are a lot of facts and data dumps stored here. Consult those not urban legends.

You have probably seen our large Miata Cooling system thread. If you haven't I would suggest starting there. Just facts, no propaganda.

Meanwhile I skimmed this thread but I'm not entirely clear on what your current setup is.
Please fill in the blanks:

Power level (approximate)?
Stock or oversize intercooler?
A/C?
Radiator?
Reroute? -No
Radiator ducting, sealing? - No
Hood vents? - No
OEM or custom full coverage undertray?
OEM or aftermarket fan shroud?
OEM or aftermarket fan(s)?

You're on the right forum to solve this problem if you are willing to do the work and spend the money required.

Was hoping you'd chime in here, Thanks. I've specifically searched around here using your name as a filter since i know this is your domain. This site is a treasure trove of information, although there's so much info to process it becomes exhausting at points lol. Either way, i'm digesting all the info i can. Not overly concerned with budget either, i just want to do it right. I dismissed the reroute idea after hearing that it's a no-go on the MSM, but have been revisiting that after seeing your miata cooling thread on here.

As for your questions:

Power level (approximate)? - 190 whp approx
Stock or oversize intercooler? - oversize 27x7x2.5 ebay special intercooler
A/C? - yes.
Radiator? - OEM MSM
Reroute? -No
Radiator ducting, sealing? - No
Hood vents? - No
OEM or custom full coverage undertray? -OEM undertray
OEM or aftermarket fan shroud? - OEM
OEM or aftermarket fans? - OEM

Cooling system is stock. It's done fine until lately, as it's getting warm down here in south FL and i'm not really comfortable with seeing temps in the 220+ range in simple stop and go traffic. Sounds like a reroute is step 1.

Search in Google, like this: site:miataturbo.net XXXXXXX, where the XXXXXX represents the word or phrase (in quotes) you are looking for. Much better results will be had.

I'd suspect something being wrong if you're seeing temps like that.

Mine never got hot with stock cooling system with a bit more power and modifications. Granted i did eventually end up with an Ebay 55mm radiator and an FM Stage 1 fan kit (which also never got hot), but i'm not convinced your car is working right.

I thought that too initially, so i drained and refilled with a 70/30 mix and a bit of water wetter. Burped the system (parked car on a steep incline nose up and let it idle with the rad cap off until the bubbles stopped). By every indication, i did it right. Temps hold fine if i'm on the highway or basically anytime i'm going faster than 20-30mph. It's only when pushing the car in stop and go traffic situations that i'll see those temps.

I'm also in South FL, where it's routinely 90+ degrees and 170% humidity, which probably doesn't help.

So it's bone stock with a bigger intercooler blocking airflow, and it idles at 220° in 90° weather.
That sounds normal to me.

-Swap an aluminum radiator in. Doesn't matter which, just pick a good brand. Not mystery meat- eBay IOW.
-Reroute
-cut antifreeze to 5%
- vent hood
- seal gaps around radiator

Should then idle at tstat temp, only get to 215 when you lean on it and quickly drop when you ease off.
Will cruise below 210° on hot days with A/C on.

None of these recommendations are clever or new info. Just SOP for a car like yours.

Thanks. Yep, this is what I've seen from reading around online so no surprises there. The MSM is somewhat of an odd bird however with it's fan set up and the IC pipes getting in the way of stuff, hence me framing this thread from the angle of the MSM's oddities.

Brb doing some shopping.

So your fans are off when temps are good on the highway right?

I'm guessing things aren't sealed well enough to pull enough air through the system when your fans are on. If things are stock ish then I doubt the fans are the main issue. Is the ebay intercooler covering up more surface area in front of the radiator than the MSM one?

How's your undertray looking? Any holes /damage?

Edit: phone didn't show me emilios response till I posted...

Hard to tell if fans are off cruising on the highway but yeah, they should be off unless I have the AC on. The car holds tstat temp or very close to when on the highway or anytime i'm basically cruising along at anything over 25-30mph. Only in stop and go traffic do temps start to climb. They generally don't go over 220f or so, as that's about the temp the MSM triggers the fans to go to high speed.

Basically, i can let the car idle and watch the car go from tstat temp to about 220f, watch the fans speed up, car quickly drops down to about 212-215 and then slowly heat back up and the cycle repeat itself. Effectively, the system is "working" as intended, but 220-225f is hotter than i'd prefer.

I agree, you should not see temps that high when just idling. My car runs in between 88-94C doesnt matter if I am idling, driving highway, backroads. All I have are stock fans and a Ebay 55mm just like Concealer does. I have minimal ducting in place.I did seal the fans to the radiator with some weatherstripping stuff I found at Home Depot. I run a approx 80/20 water/AF mix.

Additionally in terms of DPE, when i did install the Ebay 55mm radiator with Mishimoto fans/shroud, the car took foooorrrrreeeevveerrrrr to kick on the fans at idle or low speeds, if it ever did.

But would get hot on the highway. Like, too hot.

A panicked call to FM during the middle of my wedding trip net me a "ah yeah that's normal for aftermarket fans on MSMs." Turns out it's not an uncommon anecdote among MSM owners and FM in particular to see these cars using the fans more often at highway speeds than they do around town. Actual good fans got me sorted out, and i could watch them kick on and off at highway speeds, which again, isn't uncommon for these cars. An MSM with an upgraded intercooler w/ AC, stock ducting/undertray, and stock hood has absolutely HORRID airflow through the radiator at speed. Pressure builds up and creates this nice cushion in front of the car which not-so-conveniently gets all your air going around the car instead of through the opening.

General consensus around various other MSM owners seems to be that it's on the higher end of normal, but still normal for an 100% stock cooling system. I'm sure there's some variance between cars as well.

I also dont have an MSM, maybe the MSM is just a different animal.

I found your thread on your experience with that setup in digging around here. Seems like my situation is exactly the opposite. I drove the car 30 miles south to work today and the car held right at 195-205 the whole way down cruising at 70mph. It's when i got stuck waiting on the train to pass and idling for 5-7 minutes that i saw the car creep up to 217 if i recall correctly. Conventional wisdom would indicate better fans would do the trick here, but i'd rather completely bulletproof the cooling system and be able to drive the car as intended without keeping my eyes glued to water temps.

I agree with "you should bulletproof it." It's easy. It's just money, you can always make more.

Sounds like you know the way forward either way. :)

220F at Idle is a bit high for a stockish MSM . Is this a new issue? Any cause and effect analysis here? When did you install the Ebay intercooler? Some of these Ebay intercoolers block more air than they allow through. Makes for a crappy intercooler and limits air reaching your radiator.

Next, some second owners of MSMs have reported a similar issue as you where the radiator had been replaced by the previous owner using a new factory radiator which was the NB non MSM model (there are different OEM radiators for MSMs and NBs). This was hard for the second owners to diagnose as their cars had "new" factory radiators. The MSM forums were moved to miata.net but there has been good discussion regarding how to tell if you have a MSM OEM radiator : https://forum.miata.net/vb/showthrea...t=msm+radiator

If you have a OEM MSM radiator and it is not clogged or damaged, then you have an airflow problem. Sounds like you have confirmed factory fans are running correctly is that right? If yes, look to how your airflow is reaching your radiator. Another mistake discussed on the old MSM forum is that folks had a rise in temps when they put some type of wire mesh in the bumper opening to "protect" the intercooler and AC condenser from rocks/bugs. The mesh limited airflow just enough to cause idle temps to rise. The goal is to always have unrestricted flow entering the bumper opening and then to force this air through the radiator not let it move around it. This is where sealing up gaps with foam tape around the radiator and making sure the undertray is in place become important. Switching to a 95%: 5% water : coolant will also help as water exchanges heat much better than coolant. Switching to an ebay aluminum radiator may actually exacerbate the temp issue if you are replacing an OEM MSM radiator with a brand that does not have comparable heat exchange capabilities. If a radiator change is warranted, the Supermiata, FM, or Trackspeed crossflow models would be a better solution as they are more efficient than the OEM radiator and are not made with plastic end tanks like the OEM model.


Hope this helps.

Thanks for the feedback. It's always idled around 220f with the AC blasting in ambient temps of 85+ even before the intercooler install. Doing a bit of searching around online seems to lend itself to this being in range of normal. If i shut the AC off, temps start to drop and will settle at around 205-210f. Once the car is in motion and moving over 25-30mph, temps quickly drop down to tstat temp so it's getting airflow at motion. I've always theorized that this increase in temps with the AC on is mainly due to the car idling up slightly when the compressor engages + the additional load on the motor. My daily driver lexus is the same way and runs a little hotter with the AC on.

I confirmed it's the correct MSM rad and i don't have any mesh grilles blocking the mouth opening. Seems this is just normal operation for these cars. Will be throwing some money at a new rad and reroute in the coming days and the longer term plan is to do some ducting to make sure i'm getting every bit of airflow to where it needs to go.

You were right :(

Passenger side cooling fan was intermittently failing. Hadn't noticed it since every time i checked they were spinning, until one day I saw temps creep up at idle, popped the hood and saw the passenger fan off. getting it started by hand or hitting the shroud with a wrench got it going again, but it definitely wasn't running at the same speed as the driver fan and looks as if it's off balance. OEM MSM fan operation runs both fans at the same time, so pretty much confirms the passenger fan is bad. Ordered the FM fan kit and crossflow to start and the reroute will come next pay cycle. Going to completely bulletproof the system