odd overheating-please help!

[turbo90]

So, I put my rebuilt KA24E in about two months ago, and ran N/A for about six weeks of that time, while waiting to afford a new turbo. It ran well, but it overheated just a little bit one hot day after a two hour highway drive. At the time it had the old turbo exhaust housing and a blockoff plate where the center section would be that leaked a little exhaust. I figured excess heat from the exhaust leak heated up the engine bay causing the overheating. It never ran hot before this trip, the day before this trip I put on some header wrap... Now that my new turbo is on it is over heating much more frequently, but I've noticed that it only happens when I accelerate. It doesn't take much either, easily pulling away from traffic lights will do it. Anyway, can the wrap be holding too much heat in the system?---I used a crappy ebay timing kit (I'm saving for an OEM one now) that fit a little odd, could the valve timing be off just enough to cause the heat? The bearing gaps were in spec when I built the engine and everything moved freely during assembly. I just put in a new thermostat, and new coolant about 80/20 water/antifreeze, the water pump is spinning, and the radiator is hot, so water is moving. The idle vac is good, and the engine runs strong, haven't done a compression or leak-down test yet. I'm going to take the wrap off before I go to work in the morning to see what happens. Any other ideas????????? Thanks for the help.

[Import_Ant]

Anyway, can the wrap be holding too much heat in the system?

no. if anything it will HELP by reducing your under-hood temps. the only danger heat wrap poses is it causing the metal of the exhaust to get hotter which would cause it to crack it but can only HELP resolve heating issues. not cause them. the wrap is just insulating the heat IN the exhaust. not amplifying it. it's just keeping it from radiating to the engine bay.

I used a crappy ebay timing kit (I'm saving for an OEM one now) that fit a little odd, could the valve timing be off just enough to cause the heat?

If you are talking about a timing SET (cam gear, timing chain, guide, tensioner) you'll know if there's anything wrong w/ your timing when you take a light to it. some signs that its off would be intermittant back-firing and dead spots in your powerband. it'd be a good idea to take a timing light to it if you are in question at all. best case scenario is you verify its on, worst case scenario you find it off and correct it.

I just put in a new thermostat, and new coolant about 80/20 water/antifreeze, the water pump is spinning, and the radiator is hot, so water is moving.

did you remove your radiator and clean it out? when I did my turbo install I pulled my radiator and sprayed it with a hose. you'll be surprised how much dirt and crap can find its way between those fins. that will help your radiator perform its duties especially with the reduced airflow it's getting with that intercooler in there. secondly I'd adjust your water/coolant ratio. I understand coolant doesnt have any cooling properties, it DOES keep the water from boiling. once that starts to boil you're pretty much screwed. try changing it AT LEAST to 70/30 coolant/water and see if that helps. also did you burp the system? there is a bleeder valve on your upper radiator elbow that can be removed. you fill the system with coolant until it comes out the hole and you have an air-free water-jacket and no burping to do.

Some things you can do to reduce under-hood temps:

keep that heat-wrap on! it's helping you if anything.

shim your hood. add a couple of washers behind the rear bolts on your hood hinges and remove that rubber weather strip. I did it on my car and it does help keep the engine bay a good deal cooler.

wire your AC fan to turn on with the ignition. if you're running an 89-90 model car then you've got that puny fan in front of the AC condensor. right now it's just taking up dead space. might as well put it to use I'll take some pictures and show you how to wire it up if you're interested. I wired mine to my AC (since I dont have any AC components both of my fans are wired up to it.) I find it safer to screw with that circuit since it's not crucial to the car's running systems

good luck sorting out your cooling bug let us know how you are progressing.

-Aaron

[turbo90]

Deep inside I felt that the wrap would not be causing the problem, but it was a quick, easy, cheap test. I think that I may have blown my head gasket... I cranked the car while it was cool for just a second, and then opened the radiator cap, it had quite a bit of pressure, while cold. In the next few days I will do a compression test, but I think that is the problem. Kinda odd how it started to go while I was still N/A. The car runs pretty strong, 15.03 on my sixth run ever, 4 PSI T3/T4, slipping through 1st with a sub in the trunk. Oh well, if they built themselves cars would be no fun.

[nissanfanatic]

A popped headgasket is likely since you mention that it only happens on accel. Air bubbles get in and casue the thermo to close. Leak down test it. Check timing. I remember you saying AFs were good. What kind of plugs are you running?

Nice run BTW. I don't think I stayed long enough to see that one. Either way, congrats on it.

[turbo90]

Thanks, I shaved a second and a half off over 6 runs. Toming is good, I checked it with a timing light just after I got the motor in and running. I will do the leak down test tomorrow probably, and see what happens. It ran fine with the same cooling setup and a Saab T3, no hint of overheating. The only real variable is the motor that I built. We'll see I guess.

[Import_Ant]

The car runs pretty strong, 15.03 on my sixth run ever, 4 PSI T3/T4, slipping through 1st with a sub in the trunk. Oh well, if they built themselves cars would be no fun.

nice pull. is yours at 9.1:1 or 8.6 compression? Im running 8.6:1 compression @ .5 bar (7.35 psig) and curious what neighborhood Im at in the quarter.

[turbo90]

9.1:1, mind you that was with most likely a popped headgasket... There should be plenty more with a strong motor.