I have a question about a situation I had Saturday 4th. OAT was 90F. I have both the Supermiata reroute kit and their crossflow radiator. New water pump was installed with turbo kit as well. I had 222F coolant temps while driving through town yesterday and I would smell coolant in small bursts. I pulled over and found what looked like the radiator cap would allow coolant to spray out at times. I could also hear gurgling/boiling(?) within the engine. I have PS and AC, but I was not using AC at the time.

Back story: Friday I replaced MSPNP2 internal MAP sensor with an external GM sensor. There was a car show across town I was traveling too. A 20min drive with typical city traffic. I was not stuck in any stop and go situations, traffic isn’t too bad around me. While traveling there I was using autotune on TS and I was bringing car up to redline in 1st and 2nd to cover as many VE boxes as possible. Not driving particularly hard or fast. Mainly steady acceleration to help with autotune.

I was hoping someone could evaluate my setup and provide any feedback on what could help keep temps down. On Miataturbo.net I see that I was relatively safe as far as causing any damages but I hoped to be able to use the car without having to be concerned with the heat buildup and the spraying coolant cap.

Do you recommend lifting the front end to bleed the system properly? I did crack the bleeder on the QMAX reroute and got all air out during filling(felt good about it). Also, I use one of those Lisle coolant funnels during the initial filling to hopefully help remove air from the radiator side of the system. I ran the car up to the 195F thermostat temperatures.

I wonder just how critical is sealing around intercooler and intercooler piping? I’ll attach photos of the gaps I speak of.

***TIA!!

Car specs:

1994 base
Kraken turbo kit w/ 7in intercooler I kept AC and PS.
Gt2860 turbo 8.5psi
Supermiata crossflow & reroute
Using 1 OEM fan *currently*

 

Photos as stated

Intercooler fit

Gap along side intercooler under tow hook

Intercooler bumper and underbody tray gaps

Another pic

Hot side to intercooler

Cold side from intercooler

 

Either your cap is bad or more likely your fan isn’t up to spec. An oe fan was specd for 120hp, you’re now around double that. I’m not too surprised to see 220+ in those sorts of ambients.

 

To what extent do you go to seal all the gaps? I’m going try to seal them as best as possible but I’d like to find a good product for that. Need to do some research.

You can’t tell in the picture but the bottom of the IC sits below the black plastic “mouth” shroud. I removed a rectangular section for the IC to fit. So the picture is showing the IC shows the gap in the black shroud and the mounting screw on that shroud for the splash guard.

 

It’s hottest day I’ve had it out so far. The thing is is that I got occasional whiffs of coolant smell. I don’t know how fast the coolant would dry but a pulled over within 2-3 minutes after I caught the last whiff. Popped the hood and couldn’t find any “wet” coolant. Would it dry that quick being that it was boiling? See pics…Here’s what I did see.






ALSO;

What’s overheating temps? I read like 250 is failure temp.

What temps would be normal considering the added turbo?

 

Are you running aftermarket fans/shrouds? Make sure your fan is running correctly (not backwards). Have you vented your bonnet? Yes to lift the front when bleeding the coolant.

If I am reading your photos right the incoming air can go around the sides of the cooling stack and out into the wheel wells. Sealing the incoming air means making sure it all has to go through that stack, not around it. There are threads on this, including this one entitled 'Miata cooling system thread' .

 

I am running the OEM primary fan not the AC fan. It spins correctly.

I have not vented the bonnet.

I will work to seal the gaps as that seems to be a must with the new mods.

I’m very hesitant to vent the hood.

I’ve just read that an IC to close to the mouth can cause overheating. But wouldn’t the air just go through the IC and into the radiator and still cool the system. Or doing so results in warm enough air to prevent adequate engine cooling?

Thank you sharing the other thread. My search inquiries seem flawed. It’s hard to find the thread that has the issue I’m looking for.

 

I think your last crossed with mine.

First up, new radiator cap. Next, burp it again, with attitude and funnel.

Read that thread, and then browse some other build threads here. Sheet plastic, corflute, sheet aluminium, rubber strips, aircon tape, racer tape, lots of products around that will work for ducting/sealing - at this point you want function over pretty. But first, work out where the incoming air is bypassing your radiator, and if you have to shift the IC back (or it is too big), fix it -- that should be a high priority, if in fact it is blocking the mouth, obviously nothing is going to improve cooling if the air can't get in in the first place.

 

Maybe rent or buy a coolant pressure tester and put it up at 20psi, there is a lot of evidence of dried coolant in those photos, maybe just one of the small ~5/16" hoses, they tend to get ignore while everything else is replaced.

The reason we're saying cap is they're supposed to open, allow coolant out and into the over flow. If it's opening too soon, that's a problem. But if the fan isn't strong enough or there's a leak, you've gotta fix that first.

I have a bone stock air guide, barely trimmed under tray, no other "sealing", single $200 spal fan, SM rad/reroute, and no over heating issues in traffic. It'll get to 205-210, but fan keeps it there in 90* ambient. Previously I had a single MSM fan (supposedly a bit better than NA), and it would creep to 215-220. Hence my immediate response to upgrade the fan.

 

No A/C fan, FMIC and A/C with no hood vents is going to run hot. OEM primary fan is enough for cars w/o A/C but insufficient to draw enough air through is slow to moderate speed traffic in warm weather with an FMIC and condenser. At speed, the hood vents will drop pressure under hood enough to vastly overpower any airflow that any fan can generate. I know you don't want to add hood vents, but that and a second fan are what everyone here with first hand knowledge is going to recommend.

 

The cap on my Mishimoto radiator failed recently and when it did had my radiator overflow spill over and left a big puddle of coolant on the floor of the garage. I'd definitely be looking at the cap based on the dried coolant over by the neck of the radiator.

I didn't notice a huge difference in coolant temps when adding hood vents. I'm sure they help, but it wasn't a night and day difference for me. I still struggle with cooling with ducting, 2 OEM fans, SM Rad + Reroute, 180 C thermostat, hood vents, etc... Granted that's only at autocross or on track, but still. I still have the AC condenser in place, but rarely can't use AC as it causes coolant temps to rise rapidly.

What temp is your fan set to turn on at? If you can source an OEM AC fan for a decent price I'd say it's worth throwing on.

Home Depot Racing has a lot of AC sealing foam products that can help seal the gaps around the rad. I ended up cutting this stuff down to fit better after I took this picture, but you can take the 2"x2" foam and wedge it down the sides of the rad pretty easily. The top can be sealed with ~1" expanding weather stripping. I've had this foam in there for a couple years at this point and haven't had issue with melting or flying out at speed. Not sure how much it does, but for $5-10 I think it's worth trying.

 

GeeEmm,

I was leaning towards replacing the radiator cap as well, it felt kinda weird going on to begin with. I'll definitley raise the front and burp her again. peace of mind if nothing else.

Thank you for the product suggestions to blocking the gaps! I've never heard of corflute or aircon tape!

**edit aircon is British for AC**




Curly,

Great suggestions my guy! I'm going to pick up a coolant tester. One of the few things I don't have. The SPAL fan, is that something you picked up from FM?

 

Emilio,

No...no AC fan. It was a tight fit and I didn't want to completely cut up the OEM one. I had to start somewhere, and I had read other people having success with using only the primary fan (not clear on their AC status though thinking back). FMIC (FlyinMiata intercooler?) is that what that stands for?

Another dumb question.. Will the AC fan turn on at high temps regardless of AC use? I don't use it much to begin with, but I also don't want to get rid of it.



Thank you

 

Interesting results with the hood vents.

I'm running the 195F T-stat, the fan is set to turn on at 200. I have an AC fan.


**This gonna sound silly as it does while typing it** In the event of future proofing the car and if it were to ever be returned to NA-. I was trying to keep the OEM parts I removed in as close to their original condition. If I was to use the OEM AC fan, I'll need to cut down the shroud quite a bit to get it to fit the crossflow radiator and intake. That being said, Curly's suggestion on OEM fan performance meant for original HPs as compared to the new power output, it makes sense to me to install higher preforming fans.

The foam around the radiator is a fantastic idea for sealing those tight spots. Thank you for that nugget!

Also, I love that HomeDepot Racing is a nice sponsor/vendor in helping with engine cooling needs!! LOL

 

Fair enough. Upgraded fans are one of the things I haven't quite explored yet, but probably something I'll look into now that my main fan is on the fritz. IronHydroxide was able to get some Chevy Sonic fans to fit his radiator with some minor modifications. Apparently they fit pretty well and seem to perform well also.

HDR is the place to be. They're indispensable and I wish they would sponsor me lol

 

If your problem is in traffic, fit the A/C fan and wire them together. Cooling is a priority, I don't know what you have that makes modifying it necessary, but do it. Did I mention cooling is a priority?

Re the foam, you want furniture foam, closed cell not open. But open cell better than gap. I have seen pressure pack expanding gap filling foam used, sprayed into a plastic bag in the gap, or maybe inserted after the bag has been tied off. Didn't work for me, but I didn't persevere.

 

For track use without ac, we have had good luck with the single primary fan. The extra fan is needed for street use when there isn't enough air flow. Funny thing is having the fan there actually reduces total air flow at high speeds when it's more about pressure differential coming through the nose than anything the fan can generate.

 

One more thing to check, because it’s an insidious problem that is hard to detect…

Make sure that the radiator overflow line is connected to the siphon fitting on the coolant reservoir cap, not the vent fitting. I bought a used Miata that had them backwards and it made it so that water would leave the radiator, but would never be sucked back into it. I ended up with a gurgling cooling system that was missing a lot of water.

 

Cooling is a priority is well noted!

I fiddle f&$@ around lot in determining the best course of action for almost anything/everything I do. The car is my toy so I have time to do it up right.

A pet peeve of mine is having to redo something. It definitely happens but I try my damnedist to do it right the 1st time.

 

beerbaron,

Thanks for the suggestion on this. Part of the turbo install I did a bunch of regular maintenance tasks, of which I flushed the cooling system. There was a lot of brown sludge and pretty thick in the overflow reservoir. That’s really when I noticed the difference in the ports. I cleaned the tank during all that and made sure it went together properly. Switching the hoses could very easily happen if one’s not paying attention.