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Old 06-30-2008, 11:11 AM   #21
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Originally Posted by m2cupcar View Post
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.
Did try this and didn't see any bubbles but good point non the less.
Thx,
-B
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Old 06-30-2008, 11:21 AM   #22
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Originally Posted by mtncrvr View Post
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 wouldn't bother....this is trivial and not the source of the issue.



only a few things would cause overheating:
  • stuck closed thermostat.
  • leak. If the system cannot maintain pressure, it lowers the boiling point of the water.
  • Too much cap...If you have something like an 18psi cap on it, i can almost promise it's going to leak.
  • Air pockets. Was the system burped properly? You should idle the car without the cap from cold. Once the thermostat opens it will "burp" you can then squeeze the upper and lower hoses and try to remove all the air from the lines. Then you top it off and replace the cap and fill the resivour.
  • No Fans/Airflow.
  • Blown Headgasket.

I wouldn't bother with the undertray in your case, the scooper does a good enough job of sealing off the bottom...with that size rad and the scooper, it shouldn't be overheating. I'd be looking for pinhole leaks on the small lines and bad "seals" on the hoses. Try running without a thermostat, rule that out. worse case scenario is a blown headgasket.
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Old 06-30-2008, 11:48 AM   #23
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Originally Posted by Braineack View Post
I wouldn't bother....this is trivial and not the source of the issue.



only a few things would cause overheating:
  • stuck closed thermostat.
    ->replaced - this is opening (have good pressure on top hose and it's nice and hot)
  • leak. If the system cannot maintain pressure, it lowers the boiling point of the water.
    ->still very possible - will look into this
  • Too much cap...If you have something like an 18psi cap on it, i can almost promise it's going to leak.
    ->16psi cap on for now, I also have a 13psi new cap (I can run the lower cap also to be on the safe side).
  • Air pockets. Was the system burped properly? You should idle the car without the cap from cold. Once the thermostat opens it will "burp" you can then squeeze the upper and lower hoses and try to remove all the air from the lines. Then you top it off and replace the cap and fill the resivour.
    ->forgot the burp (I normally do this, but I finished at midnight Sat and forgot, so will open the cap and burp it properly). Fyi: it started overheating b4 I opened the system but then again I suspect the old thermostat wasn't working so I could have fixed one prob when I replaced that and introduced another (I did tstat first last weekend and the pump etc this weekend).
  • No Fans/Airflow.
    -fans running properly, everything stacked close together and I don't have a ricer-big fmic mounted in a retarded way so airflow should be fine (although prob wouldn't hurt to insulate around things)
  • Blown Headgasket.
    ->Yeah this is the one I'm hoping to avoid since you gota take soo much off to replace it.. I just spent a good day/night in the garage (w/o the beer this time = teh suck). I'm also not seeing any normal tell tail smoke but it could still be a hairline crack in the gasket... (fingers crossed it's not)

I wouldn't bother with the undertray in your case, the scooper does a good enough job of sealing off the bottom...with that size rad and the scooper, it shouldn't be overheating. I'd be looking for pinhole leaks on the small lines and bad "seals" on the hoses. Try running without a thermostat, rule that out. worse case scenario is a blown headgasket.
I did replace the tstat but I can def pull it out (was thinking to pickup a mazda tstat with the dual springs anyway) but will need to pickup a new gasket to do this test first. And yeah will keep an eye on the hoses and replace any that look cracked at the hose clamps (there's several tie-ins at the bottom hose area that are a bit on the cracked side now, will be cheap n easy to replace them (although messy :-P).

Thx,
-B
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Old 06-30-2008, 12:15 PM   #24
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the car will burp whether the cap is on or not. air rises and will sit at the top of the radiator and not circulate back down to the motor. when the pressure rises enough to open the relief valve on the cap the air will escape first.
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Old 06-30-2008, 12:53 PM   #25
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Check your heatercore line for leaks, and check your lines under the intake mani that go to your factory oil cooler. At 140K those are due for replacing if never done. Mine leaked around the clamps very slowly, I wasn't overheating, but I changed them out at 120Kish to prevent this kind of ****.
You should not be overheating with the mods that you have, not nearly, so there is a problem somewhere (duh!). If all hoses are good then do a leakdown.
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Old 06-30-2008, 12:58 PM   #26
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Yeah leakdown was my next q - this would show a cracked gasket and I guess i can assume I'm good in terms of rings etc since no loss of power or mixed coolant? Rather my q is that a leakdown can show a number of problems, but it would be most likely the gasket if the numbers or one of them come back bad in this case?
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Old 06-30-2008, 01:02 PM   #27
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In a leakdown you should be able to hear where you are leaking.
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Old 06-30-2008, 01:08 PM   #28
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When I had a temp issue a few weeks ago, I had to adjust my timing. it was running way to advanced. I then let the car run from a cold start with the radiator cap off and sure enough when the tstat reached it's opening point I saw the level in my radiator drop significantly, added fluid and did not have a temp issue from that point on.
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Old 06-30-2008, 01:49 PM   #29
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I'll add a timing sanity check to my list but I'm pretty sure it's solid (made marks on the belt when I did the pump, I also clamped the belt to the cam gears so I only had to line up the crank gear with the mark on the belt and crank didn't move when belt came off). I didn't need a new belt when I changed the pump since this one only has 15K on it.

Yeah I know I shoulda changed the pump when I did the last belt but pump was ok anyway so go figure (that was when the belt slipped massively under boost so the existing pump was far from time to replace, current belt = nice and tight). Will hit it with the timing light and have Bell sanity check my maps since there's not really anyone on here running Xede (maybe one person and yeah I woulda prob gone the MS route if I were to do it over, but it works for now, may change in the future).
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Old 06-30-2008, 10:56 PM   #30
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Okie - may have this under control

-it did burp and more importantly never trust your kid when they say that BOTH fans are running and I did ask about both..... My bad I should checked behind him - I thought maybe the dual fan mod splict went bad so I was fiddlin w/the wires at the ecu and asking to see if they were both on... Main fan (driverside) is dead (there's power at the connector, but she ain't spinnin). Fan replaced (generic performance fan for now blows better than stock but it's cheaper than driving my truck to work one or two days) - seems to be working now, won't really know till I hit the 100 deg temps on a test run but boosted heavily and no probs wAC on both in city driving and hwy in 80 deg temps. Sorry but thx for the great thoughts, should make it a sticky or a check list anyway (def going into my list). Will edit original post to reflect resolution. Thx again.
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Old 06-30-2008, 11:17 PM   #31
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DOH! did any of us think to ask if the fan was working?

Hopefully you got it figured out.
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