Some background.

I used to have a PWR radiator installed. I bought a Flex-a-lite fan kit and installed it after doing the last coolant reroute. As usual; the guys in the shop messed it up and when they installed it the fans would brush against the radiator. To make a long story short; both fans broke and punctured a hole in my radiator.

I then bought 2 new fans and a new radiator (the 55mm Mishimoto) and installed both things. I was still facing issues so I decided to take out the BMW tstat and install an OEM one. As I mentioned in the WTB thread I started, I couldn't get one locally so I decided to test the car without any tstat. I have to report I don't like what's happening.

I plan on taking the car back to the shop tomorrow to check the water pump and see if somehow there's a problem with it.

Now on to what I'm currently seeing:

As soon as the car reaches operating temps around town the Autometer gauge shows temps climbing to 210* even while driving the car like an old granny. Oil temps also climb around 30* higher than what used to be normal temps.

Observations:

1) I took out the spark plugs to check whether I had any problems with my headgasket. The only thing I can see is that I'm running pig rich but there's no mix of water and oil.

Can anyone offer any suggestions about what to do next?

Thanks,

Rafa

 

Does the radiator hold pressure?

Is combustion gas getting into the coolant (smell the radiator hole for signs of exhausty smell)?

Is the system adequately burped and there is NO air in it?

I had an overheating issue and it was caused by, of all things, a dying Koyo drain plug leaking all my coolant out. temps would go nuts at idle probably because of steam pockets around the sender.

 

It's possible that with no tstat the water dosent spend enough time in the radiator to cool down enough. The water is moving through the system to fast. Also like Matt said, be 100% sure there's no air in the system.
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If he's seeing problems "driving like a granny", the water pump probably isn't pushing the water through the radiator too fast, but maybe

 

Went down to the parking spot to check what you asked. No smell whatsoever. Weird thing just happened. I turned the car on and let it idle for a few minutes. Took it out for a trip around the block and decided to step on it in second gear. At around 5,000 rpm it bogged down for a second and starting misfiring. It won't even idle properly without the A/C on but coolant temps didn't go above 180* during all that time.

FWIW, I changed the Mishimoto radiator cap that came with the radiator (19lbs cap) and put the one I was using with the PWR radiator before (13lbs one).

Could the water pump have been clogged? I ask because all these issues began to happen after a local guy "fixed" my old radiator. I wonder if some of the original welding he did has gotten into the system. Can this happen and if so; what can I do about it?

BTW, thanks Matt and Phil for the assistance.

With regards to Phil's advice about making sure there's no air in the system. I refilled it with water after taking the old Tstat out and also checked it this morning and found it was totally full.

 

Could you please take some pictures of your current hose routing (because I know it isn't stock anymore)? I'm trying to remember the details. Do you still have the restrictor in that hose we talked about before?

 

just a quick thought-
Once the car has cooled, pull the rad cap so you can watch the coolant and then rev the engine. Do you see bubble action that intensifies with the increase in revs?

 

I'll go down in a few minutes and take some pics. I don't have the restrictor hose anymore. I basically went back to my original coolant reroute minus the tstat I couldn't get locally.

I'll post pics in a few minutes.

Actually the car cools down pretty fast. I'll do this also when I go down in a few minutes and report on what I see.

Thanks shooter and Rob.

 

Did you burp the system?

 

Pics as promised.

Please bear in mind that I can't get the autofocus to work properly with this camera after only 1 minute of turning it on.

Some of them were clearly out of focus. I'm going to go down again and take additional pics.

 

No clue about how to do that Jason.

 

My current reroute is basically the one on this thread: https://www.miataturbo.net/forum/t23314/

sans tstat (for the time being) and thru the coldside instead of the hotside.

Some additional pics:

 

I left the OEM thermosensor in its original position. I used a bended stainless steel pipe and hooked it up to a hose up to the radiator.

The third pic is of the Autometer thermosensor which is placed in that stainless pipe as it comes out of the back of the head.

 

That hose going from the back of the head to the reroute tube looks like the high spot in the cooling system for sure. That's based on its relation to the cam cover vs. the rad filler up front. What happens is air gets trapped in that high spot and inhibits coolant flow past that point. Usually the system purges the air ok, but a large tube like that with air in it probably wouldn't. You could jack up the front of the car to get the rad filler to the highest point and then run it to see if the coolant system would then purge itself of air (burp).

You can see how my exit is kept at the head's coolant exit height at the back. It stays that way to the rad.



You could also add a filler neck back there inline with that hose for burping (and filling).

 

or stuff a swirl-pot back there.

 

That's exactly what I was thinking from looking at the pics.
That is also a good idea. Essentially, you need to be able to open the cooling system at whatever point is the highest and add coolant/water until there is no air in the system. The stock system is carefully designed to have the radiator cap at the highest point. You now have a situation where air cannot come out of the head and back to the radiator. Do you see what I mean? You really don't need a large opening or a filler neck back there where that hose is. You just need an opening big enough to add some water and let the air bubbles out. But a filler neck like the one pictured could work if it was located at the highest point.

Isn't this fun, Rafa?

 

Let me start by answering your last remark first: It's fun. I get pissed and curse a lot but I have to admit, I also learn a lot! Many thanks to all for assisting. It's really good to know I have a place where I can ask guys much, much more knowldegeable than me for advice and get it

That is precisely why I subscribe to this board!

Shooter: I totally get both your explanation and Rob's. I took a long look at his pics and no question about it: his hose is never higher than the radiator cap. What I'm still trying to decipher is whether I can put a pipe in the same location Rob has his. My radiator cap location is closer to the passenger side than his which could work to my advantage.

BTW, hustler mentioned a "swirl pot" and I've read some past post where he also mentioned it but I have no clue what that is and how it works so... if someone can explain it I'll be most grateful

 

a swirl-pot spins the water into a vortex, air goes to the center and bleeds out.

 

Thanks for that info hustler.

I triple checked everything this morning. Water pump is working fine.

Rob and shooter: I think your remarks about the hose connected to the back of the head is spot on. It is definitely above the radiator cap. I can see higher temps on the back of the head and I'm pretty convinced it's due to air in the system.

I'm going to try to make mine exactly as the one in Rob's pics.

Many thanks,

 

your tstat is on its way sir