Radiator seals? Let me know when you find those.

Hi all,

My 99 GST recently started overheating, according to the factory temp gauge, but only while I'm idling for a period of several minutes. The car has not done this before and my modifications have not changed at all within the last year or so. Once I get moving again, the gauge drops back down to halfway.

I haven't replaced anything yet as this just started yesterday, but what should I look to replace/fix? Both upper and lower radiator hoses feel hot and both my fans are kicking on. The timing belt was replaced about 20,000 miles ago and the water pump was allegedly replaced at the same time (I don't have the service record as the previous owner had the work done).

I suppose I should start with a new t-stat, radiator cap, and perhaps flush the radiator.

Any ideas/suggestions?

Thanks

check ## coolent if its low u might have a leak otherwise replace the thermostat

Yea I would say thermostat also. I had that problem in my honda civic. When I would come to lights and have to stop the engine would overheat but as soon as I got going I guess the airflow going to the engine bay would cool it back down and it would go back to normal

omartsi said:

check ## coolent if its low u might have a leak otherwise replace the thermostat

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Coolant is nice and topped off... I added some just for the heck of it but it didn't make any difference

Jdiddy2k4 said:

Yea I would say thermostat also. I had that problem in my honda civic. When I would come to lights and have to stop the engine would overheat but as soon as I got going I guess the airflow going to the engine bay would cool it back down and it would go back to normal

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It's a cheap part... figured I would start there!

you could always buy an aftermaket gauge my stock ones acts weird somtime at idel it says its over heating and other its when it going down the road you know whenever it feels like it . i got an aftermaket and found out it was the stock gugage good luck

daveyfx said:

Hi all,

My 99 GST recently started overheating, according to the factory temp gauge, but only while I'm idling for a period of several minutes. The car has not done this before and my modifications have not changed at all within the last year or so. Once I get moving again, the gauge drops back down to halfway.

I haven't replaced anything yet as this just started yesterday, but what should I look to replace/fix? Both upper and lower radiator hoses feel hot and both my fans are kicking on. The timing belt was replaced about 20,000 miles ago and the water pump was allegedly replaced at the same time (I don't have the service record as the previous owner had the work done).

I suppose I should start with a new t-stat, radiator cap, and perhaps flush the radiator.

Any ideas/suggestions?

Thanks

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if you cover all the basics and still get the same thing, change the coolant temp. sensor. that sensor goes crazy with temp readings when it goes down or starts to. usually the coolant temp. sensor will screw with the guage readings usually at idle or low rpm driving. like parking lot driving. it is also rather difficult to test the sensor, as the process includes putting the electrode in a bowl of water and cooling and heating the water while testing voltage values.

dude i took my thermostat out! and my car didnt over heat again. take that sucker out. you wont have heat but yea .

greddyturbo19 said:

dude i took my thermostat out! and my car didnt over heat again. take that sucker out. you wont have heat but yea .

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umm......... why would he do that when a new thermostat costs like 20 bucks?? if taking your thermostat out fixed your problem you just need a new one. then you'll have the luxury of heat again.

I'd start by replacing the thermostat and make sure you bleed the cooling system correctly. If you can then replace the water temp guage with an after market one, in my opinion the water temp, oil pressure and the factory boost guage are not very trustworthy to begin with and should be replaced as soon as one has the money to get rid of those things. Be absolutely sure that your fans are kicking on I had a car once that did the same thing and while I was driving it would be fine since their was adequate air flow but at a stand still due to the fan malfunctioning it would tend to overheat.

Check your fans

Hi, My car never used to over heat at all. In fact the heater would never really blow hot air, but more of a warm stream of air. Yesterday I was out having fun with the car doing some canyon runs and I was over 5000 rpms for the majority of the time. All of a sudden I looked down and noticed the temp gauge all the way up high. I let the car cool down and noticed there was water all of the ground under the car. I ended up going home and on the freeway the car would not over heat at all at cruising speeds. But as the rpms increase, the car's heat will gradually increase also. It seems as if the amount of overheating is directly proportional to the rpm speed. TOday I took out the thermostat and ran the car. It will still over heat above 5000 rpms. I also changed the radiator cap and the car still overheats. I recently installed an ssac fmic and I don't think it has anything to do with the overheating. I also don't see any water spills anywhere. I don't hear any noises from the water pump. I also did a compression test-- cyl 1-- 145psi cyl 2 --- 155psi cyl 3--- 165psi cyl 4----170psi. I am pretty confused here and any help is very appreciated.

Well, I just read up a little bit on compression to double check what I was thinking, you're within the service limits on compression, but I don't think you're supposed to be 25 psi between cylinders. If I'm not mistaken you're only supposed to be under 14 psi between cylinders, so noting that you have 145 on cyl 1 and 170 on cyl 4 indicates a problem itself. Maybe you messed up your HG or warped your head during your spirited runs? (You may have ran it hot for excessive time), that's just what I'm thinking. Your fluids aren't low, and it's still overheating with the thermostat out? Sounds like a HG to me.

I read that your lowest cylinder shouldn't be more than 14 psi less than the "average" of your other cylinders, in your case your other three cylinders average out to 163, so you're still over the limit there (163-145=18), so I'm still thinking it could be your HG or head.

If I'm wrong then someone correct me ^^, hopefully you get it figured out.

Most likely your water pump is broken or you have a cylinder leak. Try a leak down instead of a compression test.

1gDSM4g63 said:

Most likely your water pump is broken or you have a cylinder leak. Try a leak down instead of a compression test.

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i agree with the leak down test rather than compression test. that would be the best method of attack. but, there is no way you have a water pump going out. the water pump is driven by a drive belt, so if it's going out it will quit pumping, period. it shouldn't matter what rpm the engine is running. and if it's like any water pump i've ever had go down you will no doubt hear the bearing sqealing like crazy when its locking up.

the liquid you found everywhere when you were out driving most likely was blowback from the coolant reservoir. are you getting any water/antifreeze in your oil?? by a process of elimination it's most likely the headgasket as stated before.

Thanks for all of the quick replies. Yeah,, I purchased the car with the compression numbers it has. When I bought it it never over heated and now even with the same compression numbers it started to overheat. I am gonna run down to autozone and use their block tester right now. I am also aware of the psi differences between cylinders but the car runs very strong. I am saving up for a 2.3L engine right now but I am in no financial shape to drop a new engine or replace any parts right now so it would really suck if is a head gasget but I'll go and try the block tester and get back to you guys. I will also have a leakdown test performed as well. Is there anything else that comes to your mind that might be a cause of my overheating??? Thanks guys.

If you don't have combustion gas in your cooling system, and the water pump is verified to be ok, you might look at your radiator. It is 12 years old after all if it hasn't been serviced or replaced.

+1 to above, could also be a reason, and that's why he's a wiseman! My plan of attack would be to rule out the smaller easier to do things before you start ripping apart the head to see if it the headgasket, just what came to my first when you explained the problems. Grab your water pump and see if you can move it around, it might not be squealing but it may have went out. Definately do the leak down test and let us know the results. They have a group buy on the koyo radiators going on right now, maybe that could be the first thing you attack and try and rule out?^^ hopefully you get it figured out and hopefully it's not the HG!!

Ive been having the same problem and it was after I installed a 16G and big fmic as can see in my images. I replaced my radiator with a koyo and new thermostat and still no luck :-( . and it can drive for about 5-7 miles before it starts over heating without trying to boost.

At least there's two of us with the same problem. Jk. My system has no leaks as far as I can see and THe upper radiator hose has lot's of pressure in it. Would it still have pressure if the Water Pump was bad. I am also thinking about the heater core and the heating system. Is there anything I can check out there?? Going to get the hydrocarbon sniffer test done right now. BRB.

Okay, I just did the block test and it revealed no hydrocarbons present in cooling system. So the head gasket is okay. So I also did a wet test a few days ago and the loss of compression is due to cylinder rings. I guess I now need to test the darn water pump. It seems like such a pain in the ass but I guess it needs to be done. But the system does build up water pressure. Wouldn't there be little to no pressure if the water pump was bad??? IF there is anything else I can check before I have to do a timing belt job please let me know. THanks again to all of you who've been so helpful.

50trimmed1g said:

I recently installed an ssac fmic and I don't think it has anything to do with the overheating.

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IMO that is affecting the overheating also. I assume that a 2g is similar to a 1g in that it has a black plastic piece that you had to remove to fit the FMIC? It is an air duct for the radiator. It directs air thru the radiator and without it the air will follow the path of least resistance. Under, around and to the side of the rad & FMIC.

I fought overheating issues right after my FMIC and this is a great solution. http://www.dsmtuners.com/forums/turbo-system-tech/245981-fmic-ducting.html

Edit: Have you pressure tested the cooling system? They have testers you can rent at auto zone.

usually when a water pump goes down it will squel first. thats the bearing inside the pulley locking up. once it locks up it wont pump any coolant, so the radiator hoses will only have what coolant was in them when the water pump went down. also when the water pump finally locks completely up it will burn the belt off it or just throw it off. however i'm quite sure that things can happen quite differently on different cars and different situations.

And out of curiosity I just stuck the block tester near all of my exhaust fumes from the tailpipe and the fluid didn't change color either??? I don't have a cat by the way.????? Now I'm not even sure if the block tester works