2G Randomly started overheating

[spyderdrifter]

So I got to work this morning and sat there in my car for 10-15 minutes like usual just to let my oil cool down and so forth. After that I noticed my temp gauge reading way hotter than it should and my coolant was boiling in the over flow reservoir. The last time I worked on the cooling system was back in February when I put my Mishimoto radiator back in. The system was fully burped and replaced the rad cap the same day. The water pump, thermostat, and both temp sensors were replaced last summer. Since the rad swap, the cooling system hasn't had any issues and has run just fine and now this. The drive to work showed no abnormal Temps either. Any ideas out there? My only thought is maybe the water pump since it's not an oem unit, but there's NO leaks anywhere. My parts list is current except the fmic has NOT been installed yet. I know that will cause higher Temps and have planned for that once I do install it.

 

[luv2rallye]

Some ideas:
http://www.dsmtuners.com/threads/overheating-cause-thats-rarely-mentioned-and-how-to-test.378462/
http://www.dsmtuners.com/threads/help-im-overheating-heres-how-to-fix-it.200575/

 

[spyderdrifter]

Thanks for the info, those are great links. This has been bugging me all day while at work and I'm leaning towards the water pump possibly being bad since it is an aftermarket unit.

 

[96 GSX LOVE]

Could have just got cranky since it has only did it once. It is a dsm . Did you have the ac on? A good way to check the water pump is to rev it up a little when it starts to overheat if it cools back down the water pump is usually the suspect.

 

[spyderdrifter]

A/C was off since I removed the system. I opened the hood and the coolant was boiling in the bottle. I just ordered a new pump since I believe it 5 be the cause. I will however be verifying that after work tonight. If it's circulating though, I'll just have a spare one to horde. I'll give the rev idea a try as well and report back.

 

[stars]

If it was mine, I would first suspect the thermostat first. If the thermostat is stuck closed it will not allow the coolant to circulate. Second I would get a factory Mits rad cap. If that still doesn't fix it then next time it overheats check both the upper radiator hoses. See how hot the upper rad hose is compared to the lower radiator hose. If both hoses are equally hot then your water pump is not circulating the coolant. Now you can replace that water pump and know that you got your problem fixed.

 

[spyderdrifter]

All the parts such as cap and t-stat are oem and are no more than a year old. Will be replacing the water pump this weekend.

 

[luv2rallye]

Good time for timing belt if it's over 50k miles.

 

[spyderdrifter]

Timing belt has maybe 10k miles Was done last year with the current water pump, which is why this sucks. Didn't want to be doing the timing again.

 

[Roberti 2G]

I just did my water pump two weeks ago, I used a gates pump amd its leaking out of the weep hole already. It hasnt overheated yet but im replacing it tmmr along with a tstat

 

[spyderdrifter]

2 weeks is bad. Luckily mine lasted a year. I pick up my new GMB pump tomorrow.

 

[spyderdrifter]

Well I tried the rev theory after work and had no results. My car didn't even overheat after getting home and letting it run for 10 minutes. So I repeated my trip from yesterday and got here to work. Again the temp rose so I tried the reving and got results. The first time I turned on the a/c fan to see if that alone would lower the temp enough. It dropped maybe 1-2 needle widths. So I rose the rpms to 2k, temp dropped. Repeated this a 2nd and third time and it dropped back each time, so there's the proof for the water pump according to that theory. Good advice, thanks. Since all that, the temp will rise to where the needle is sitting at the top of the icon for the temp gauge and then fall back to normal without me touching anything. Picking up the new pump today and replacing it tomorrow.

 

[spyderdrifter]

Well I tried the rev theory after work and had no results. My car didn't even overheat after getting home and letting it run for 10 minutes. So I repeated my trip from yesterday and got here to work. Again the temp rose so I tried the reving and got results. The first time I turned on the a/c fan to see if that alone would lower the temp enough. It dropped maybe 1-2 needle widths. So I rose the rpms to 2k, temp dropped. Repeated this a 2nd and third time and it dropped back each time, so there's the proof for the water pump according to that theory. Good advice, thanks. Since all that, the temp will rise to where the needle is sitting at the top of the icon for the temp gauge and then fall back to normal without me touching anything. Picking up the new pump today and replacing it tomorrow.


So after initially posting this, I decided to see if the temp would lower with revving and a/c switch independently. Didn't get much for results with only revs, but did with the a/c switch. By switch alone, the temp dropped slowly, but adding revs with the switch dropped the temp a lot quicker. You test results it should still be the water pump correct?

 

[96 GSX LOVE]

I dont think its the thermostat because if it was boiling over that means it was cycling to fast and the water wasn't getting cooled down. Keep us posted so you can keep boosting happy

 

[96 GSX LOVE]

Also do you still have factory fans?

 

[spyderdrifter]

I never thought it was the t-stat for that reason, and yes, still rocking the stock fans. They still function properly and cycle when needed.

 

[96 GSX LOVE]

Well since its only when setting for an extended time an aftermarket fan would probably do the trick. As long as you have no other heating problems.

 

[spyderdrifter]

True. I just need to fix it since my fmic kit shipped today and I know that'll cause cooling issues on its own.

 

[96 GSX LOVE]

Well fans would just be a bonus anyway since your tearing it all apart IMO you should throw in some aftermarket fans to really help pull some air thru the radiator since it now has to pull thru your big fmic

 

[spyderdrifter]

I'm thinking about the aftermarket fans, and I'm also building sheet metal ducting for the radiator to feed air over the fmic.

 

[spyderdrifter]

Well, here's the final update. I pulled out the old water pump and it showed the signs of leaking from the weep hole. Turns out the GMB pump I bought was the wrong one, so I had to return it and got an Import Direct brand pump, which incidentally is the same brand that I already had on. So I suckered it up and bought it since I really need my car for work. I will order an OEM one soon in preparation for this happening again in another year, sadly. So I got the new one on, re-timed the engine and somehow forgot to remove the gear stopper placed between the cam gears and started the engine.....

......yep..... in short, the crank spun almost a full revolution with the front balance shaft, while the cams, oil pump sprocket, and timing belt remained in the same position. I was certain a destroyed my valves and maybe the piston domes from the horrifying grinding noise the came out when cranking it that one time. So after I spent 15 minutes freaking out about potentially breaking my engine, I tore off all the timing parts, reset the crank, and timing and got it ready to start again. Somehow I was lucky and my engine fired up like nothing happened. Even though the crank spun without the belt moving, none of the teeth sheared off. So I got the e coolant burped, and the test drive went fine. Engine still runs smoothly and no more overheating. It's been a long stressful weekend, but the spyder survived to drive on.

 

[spyderdrifter]

New update...

Used my car for a work vehicle yesterday since I wanted to test out on the highway. Drove just fine and had no worries. So this morning, I again got to work and let my car run while waiting to leave for the job site. It f@!king pissed coolant out this time. Got a puddle of coolant under my car now and the gauge went all the way to where the needle couldn't move. Luckily I remembered the a/c fan and rev trick and got the temp gauge back to normal and shut it off. I need new ideas on this. When I replaced the water pump I checked the oil for coolant contamination and didn't see any. Could I have been wrong and need a new HG? I have had white smoke from time to time, only at idle, and had really believed it to be from turbo needing to be replaced. All my lines are connected properly, and I have no leaks. I suppose I'll need to look again at the new pump's weep hole to verify it didn't shit itself too.

 

[evoredy]

The headgasket could fail in such a way where a coolant jacket is ever-so-slightly connected to a cylinder only allowing coolant to be sucked in during idle situations. During more positive driving, combustion chamber gases will enter the cooling system causing all sorts of overheating/boiling over issues.

Your coolant will not have oil in it or vice versa.

This had happened to me before. You could barely make out the imperfection in the headgasket.

Also, continue rocking the OEM fans (AC fan included). They are FAR better than most aftermarkets out there. Just trick them to run all the time (tuning/wiring/however).

 

[spyderdrifter]

Guess I'll need to pull the f@$ker apart and get a new HG and bolts. If it is a slight imperfection as you have suggested, would a decking be required? I know I'll have to measure for straightness, and know how to do it. Guess this will be as good a time as any to switch to ARP studs.

 

[evoredy]

The right answer is: get the head decked.

The OEM composite style headgaskets leave divots and material everywhere. The "channel" that the coolant made may have created an uneven valley on the head. Take a GOOD look, clean it well, and when you think it's ok, get it decked anyways. (I'm not saying you can't get away with it, but it's not worth it.)

I looked at your mods. Make sure to have a friend or someone log your car and verify you're not running too much timing and lean AFR's to prevent this situation in the future. Make sure you have at least a fuel pump to support that T28. When I had one, it could easily spike to 22 PSI uncontrollably.

Some more downtime, but it will be worth it. Even before you start, check everything like you said again as I pointed out the worst-case scenario. Good luck!