RESOLVED

Main cooling fan was bad - long story short I asked my kid to watch them since I thought the dual fan mod splict had gone bad and he said both were on.... Lesson learned. Again thanks for the many suggestions and hopefully it's completely fixed (havn't tested it in the 100deg temos here yet but boosted heavily and no probs).
-B


Okie (I've searched the forums first of course) my '00 is overheating (most of my **** is in my sig but here goes) and I just want a sanity check here since it is my DD and I don't want to take the truck to work (think 12mpg @ 80 miles/day):

-stock block
-2860RS (begi S3 kit, turbo and mani c-coated)
-Koyo thin radiator (the one that's 2x thicker than stock)
-stock rad fans
-16 psi rad cap (from napa)
-bell coolant reroute
-bell air scooper
-bell cold air box
-bell bypass (instead of VTA BOV)
-2.5 exhaust
-xede tuned (street tuning sessions) by Bell @ 2K' above sea level (I live ~800 above sea level) and was tuned in the summer (hot summer) for 12 A/F ratio (on the conservative side for both fuel and timing)
-no real temp gauge (just the one in the gauge cluster that sucks)
-Bell's largest FMIC
-FMIC-A/C condensor and radiator are extremely close (so close that you can mess up the fins removing the radiator) to keep air flow going
-dual fan mod (both run when one would run or when A/C is on)
-about 30% coolant mixed with distilled water (no water wetter since it made my resivor look like an alge tank - although I do have some onhand if you all think I should go that route)
-just installed a new water pump (from mazda, old one looked ok.. )
-new generic (carquest) 160 degree thermostat

I was having probs last summer in cruise conditions with the A/C turned on (with it off I was fine). So I added the Koyo and fan mods and all was good in the 100 degree summers here with 70-80% humidity - I could boost all I wanted with A/C on and no probs after the changes.

This summer is a new story, I drove to the gas station and back (think 4 miles) after letting the car warm up and boosted some on the way (but not on the way back of course to let the turbo cool) and my coolant tank is acting like a coffee percolator - air and water coming from the overflow on the radiator like mad until the coolant tank is empty... Fans are running properly.

I did the water pump, thermostat and rad cap and still same prob. Def have more water pressure with the new pump and the thermostat is def open (top radiator tube is hot and pressurized). I also did belts/oil and painted the valve cover :-) while I was at it.

Now I don't have:
-oil cooler
-underbody tray (this is a pita with the air scoop installed)
-any additional ducting at the mouth or insulation added around the radiator (it's a tight fit)
-slim mount fans ? Do they offer higher cfm than stock ?

My Friend is suggesting (some for testing purposes)
-run w/no thermostat
-run pure distilled water and water pump lube (no coolant added)
-seafoam/water clean the head (I'm thinking seafoam after seeing the horror stories on too much water going in) since I do run on the rich side and may have built up a deposit thats turning into a hotspot ?
-oil cooler

Could I have a hairline fracture in the head gasket (this happened to a friend of mine on a diff car and caused overheating) ?? But my prob is only on the hot days and I see no coolant in the oil and vise versa and no tell tail smoke from the exhaust ?

Car has ~140K on it now (30K of that is boosted at 11-12psi with relatively conservative timing and fuel) and has been well maintained (regular oil changes with either mobile one or Royal Purple 10w-30 and also has had coolant drained every summer -> winter to change the mixture (never see any gunk in the coolant fyi - it comes out clean).

I also have the oil filter relo part of this kit:
http://www.miatamania.com/Shop/ViewP...08&SortOrder=2

This was on the car when I bought it. If I go to an oil cooler I'd prefer to stick with AN fitted hoses that work with the existing kit (I guess I could buy the whole kit and sell off the parts I don't need also - but I'm short on cash after doing the pump etc and I want a kit with a thermostat).

Any suggestions on this (any of this) are welcome.

What would you use to insulate around the radiator ?? Is there some off the shelf stuff I can get at lowes etc to fill gaps ?
Do I need an the oil cooler (don't get me wrong - I want one and have a good mounting location - it's just a matter of budget and whether it will help solve this issue since I need the car up and running for my 80mi / day commute), if so which would you recommend ?
What can be used for undertray material that I could get locally at lowes etc ? The existing tray will no longer fit (I even cut it up and can't get a nice fit, and I'm not afraid of riveting or using metal tapping bolts etc).

I still wanna know why this is a problem now and wasn't last year ... very odd and on cool days car runs fine. Any help is much appreciated and sorry for the long post (figured I'd fill in as many gaps as possible). TIA
-B

 

Are you running the BEGi Racer coolant reroute or just the standard one that leaves the t-stat up front and the smaller heater core outlet housing in the rear?

 

just an idea, but with my brothers car, we couldn't solve his normally aspirated overheating issues for anything - until we replaced the coolant temp sensor.

 

Standard w/tstat in stock location.

 

If the rad is bubbling to the over flow can, then you've got a leak somewhere. Not necessarily that coolant is escaping by any obvious amount, but air is getting into the cooling system and allowing the coolant to boil. First thing to do is check the rad cap. Then I'd go through the hoses. I found a similar leak when my rad was boiling over and happened notice steam escaping near a hose clamp - but it was a pin hole in hose. Only leaked coolant when it was boiling.

 

So the heater core return line is T'd into the upper radiator hose after the T-stat, right?

 

Does it overheat while you are driving or when it is sitting?

 

Any and all thoughts welcome, in my case it's dumping coolant massively though - did his car do this ?
thx,
-B

 

Lower hose actually but yes it routes like that, turbo water return is also very close to that on the lower hose fyi.

 

Lower hose? That makes no sense at all. You rerouted it from the mixing manifold before the waterpump to the hose that feeds the same mixing manifold(or replacement) into the waterpump? It's supposed to go to the upper radiator hose where it would then flow to the radiator and be cooled before reentering the engine. Otherwise you are just throwing heated water back into the engine just like stock.

 

Sitting seems to be worse after any boosting but also seems to get hot w/o boost. Driving at normal speeds seems to help cool it. I've had a/c on every time also fyi as it helps smooth idle and it's 100 deg out (I suffer the annoying egr passage blockage problem, cauusing poor initial idle - every 15k mi but I just found the workaround to cleaning the intake passageway :-)

 

Yeah I had to sanity check this against bell's manual but you're correct.
Check out http://www.bellengineering.net/articles.php?tPath=31_34'
The S1-3 manual pages 6 and 7

 

So I will ask again because your answer isn't very clear at this point.

Where do you have the return line from the heater core going? To the T splice in the upper radiator hose flowing into the radiator or to a T splice in the lower radiator hose flowing out of the radiator and into the water pump?

btw, it's on page 8, not 6-7.

 

My kit is a bit older and doesn't have a t-splic in the upper hose - it's spliced into the bottom hose (as far as I know without going outside to look). The main purpose of their reroute at that time was to get the hard line away from the manifold (it's completely removed, and the return line is routed along the driver side of the bay, tucked under the fender) - I believe the design has changed a bit since I installed. Although I'm sure I could get a t-fitting for the top from Bell and put it in there. I'll take some picts tomorrow to help clarify for ya. The spliced in line in fig 22 and 23 (at the top radiator tube was not a part of my kit (I'm certain this was changed since I installed). The manual has been revised since I installed a year ago as this doesn't match up with the hard copy I have fyi. Got the page wrong since I was viewing on a tablet - it does funky things to pdfs :-P

 

Interesting - I'll have to heat it up and take a look underneath - the amount of bubbling is huge (think snorkeling bubbling on steroids). I did replace the rad cap (the tube to the reservoir is cable tied on since so many ppl have managed to crush the overflow outlet with hose clamps and I'm not seeing any leaks or steam there (I could carefully add a hose clamp there if you think this would be usefull, got a bag full of them for various needs). But you've raised an interesting point here - the various tie-ins to the lower rad hose have aged with my commuting and perhaps I should replace all of these hose sections to be on the safe side (wouldn't cost much or take long). Also since there is no under body pan they are subject to road debris so this is entirely possible.

 

you need to route the heater core return into a splice "after" the motor, straight to the radiator.

If it ran fine last summer, and you didn't change anything, this means you have a problem on your hands that needs to be fixed.

 

Edit: This edit was for Paul, FYI, check out figure 74 on page 22 of the install guide and you can see there is no tie in for the heater line on the top rad tube, the pict is prob from their orig manual but that's how mine is setup.

 

Thanks for the input so far guys, I'll def look into tapping the heater return into the top of the rad after the tstat. I'dd like to look into sealing up the gaps around the mouth, any thoughts on what to use for this? I'll also look for leaks, prob go ahead and replace all of the hoses and clamps where things are splicing at the bottom -I take it the turbo water return needs to go to the top of the rad also? How effective is an oil cooler in keeeping temp's down and what would you suggest? And finally the underbody pan-what can I use to make this with? Lexan? One other Q slim fans - do they flow more than oe?

Thx,
-B

 

i made something out of a rubbermaid tub/bin. cheap and easy to source.

 

Bubbling and coolant overflow with high temps is definitely significant of a closed system exceeding it's pressure limit. If you put 25psi cap on your rad, you might find your leak since the higher pressure might be enough to force coolant/steam out the leak. Though you also risk creating other leaks and making a mess.

One thing that would make compression escaping into a coolant passage (headgasket) obvious is revving the engine with the rad cap off. There would be bubbling in the rad from the compression (not heat/boiling) and it would increase with revs.