Is it possible...?

[liv2ride]

Just so you have the details on the car. It is a '90 GT with 43K original miles and the car is stock except for 40 series Flow Master, NGK plugs, MSD cap/rotor/wires and now a high flow water pump.

Yesterday I decided that I should replace the water pump because the one on the car was obviously the stocker, especially with the ordeal I experienced trying to remove the water pump gasket once I removed the pump. The coolant was not disappearing but the weep holes (both of them) were a little wet and I thought it was only a matter of time before complete failure. I found a high flow GMB reverse rotation pump at Checkers and it was a good price and included a lifetime warranty so I went with it. I also bought a replacement 180* thermostat (Prestone). After I got the pump and thermostat installed I was curious to see the temp difference if any. I started the car and let it idle for about 25 minutes in my garage and the temp never passed the 1/3 point with the headlights on (hahaha) I believe that is around the letters M and A. So this morning I wake up early so I can stop to get gas and Starbucks on the way to work to only experience three spooky but similar events. After driving about 5 miles the temp gauge (stocker) climb past half and went to the line above - I have never seen it go that high since I have owned the car. The typical level is half way unless headlights were on then it would get as high as two needles widths above mid-point. I did some reading and found that the headlights being on does affect the reading on these POS gauges. So, after the first incident I pulled over with the fear that I was going to over heat but I was surprised. I found that the radiator and hoses were hot but touchable engine was not ticking like it was too hot and I did not notice a drop in coolant (overflow), see any coolant or smell any coolant. After about five minutes I start the car back up and the gauge is below half. To make this longer story shorter, this happened two other times before I got the car back to the house but the final two times I stopped, turned off the lights and let the car idle and the temp eventually dropped below half each time. So after I got the car in the garage I jumped in the Sentra (I know - shut up) and headed to work.

After work I immediately assessed the coolant level and found that everything appeared normal. I removed the cap and started the engine so I can monitor the situation a little more. I did not find any other issues that I did not see the night before while the car was idling. I had a friend rev the car to about 2k rpms and I did see the coolant flowing in the radiator. After being scared three times this morning I decided to replace the Prestone t-stat with a 180* Mr Gasket (it came highly recommended). After replacing the t-stat and topping off the coolant I decided to take another drive. It was dark and the temp was about 75* outside. I noticed that there was a similar pattern but I refused to stop or turn off the car. I noticed that it would go to the line just above half then drop below half - cycle taking about 5 minutes each time. I also noticed that my oil pressure appeared to be higher than normal on the stocker gauge - it was about half way during idle after the car was warm. The volt gauge has always read slightly above half since I have the 3G 130 amp alternator installed.

So, the question is do you think that the problem is really a problem (i.e. wrong direction flowing water pump) or do you think this could be as simple as the gauge voltage regulator?

Oh, I used an infrared thermometer on the valve cover, t-stat housing, upper/lower intake, upper hose, lower hose and various points on the radiator and never received a reading above 220*.

Please help I am getting desperate and don't want to replace the pump again.

 

[HISSIN50]

did you bleed the system after it was open each time? you might have air (read hot spots) in there.

you are right, the stock gauge sucks. i would recommend getting a real gauge. the regulator deadens the readings anyhow - loading the electrical system should not change the reading(s), as you know.

those Mr G stats are nice, huh. i always recommend them (i live a 1/4 mile from the sun).

i would spend 20 minutes or so bleeding the system and go from there.

BTW, nice car - love the low miles, though as you know, seals dont care about low miles.

good luck.

 

[liv2ride]

did you bleed the system after it was open each time? you might have air (read hot spots) in there.

you are right, the stock gauge sucks. i would recommend getting a real gauge. the regulator deadens the readings anyhow - loading the electrical system should not change the reading(s), as you know.

those Mr G stats are nice, huh. i always recommend them (i live a 1/4 mile from the sun).

i would spend 20 minutes or so bleeding the system and go from there.

BTW, nice car - love the low miles, though as you know, seals dont care about low miles.

good luck.

HISSIN50,

Thanks for the prompt reply. I thought I bled the system each time but all I did was run the car with the cap off until I saw the coolant stirring around in the radiator. I also squeezed the hoses some to push out any air that might have been trapped in there.

What brand gauges would you recommend? I want a temp, oil pressure and voltage gauge (not as important to me as the other two).

Thanks again bro.

Aloha

 

[DMAN302]

I have had simular issues with mine after an intake install. You need to spend some time with bleeding the system, sometimes several times before she check in. Autometer is probably the most common, but any aftermarket gauge will be better than what you have.

 

[hllon4whls]

The gauges may move with electrical load if not grounded properly but it would go high and stay high until you turned off the lights.

Autometer is a good brand of gauge. Autogage is autometers cheaper brand. The autometer is noticable better quality than the autogauge. www.jegs.com and www.summitracing.com have them among 100 other places.

If you burped the system well, then you are probably being hyper sensitive to the gauge. I doubt you ever stared at it so intently before you changed the pump. You may actually be seeing the t-stat open and close. How cold was it when you were doing the drive test?

 

[HISSIN50]

one thing to try if you feel so inclined: while bleeding it (cold car, remove cap, let idle, etc - as it sounds like you did), try to have the front driver side of the car be the highest. said another way, get the radiator neck up higher than the rest of the system.

good luck.

oh yeah, other brands of decent gauges - Stewart, VDO, etc. however, one might find that AM's are the most prevelant.

Aloha.

 

[liv2ride]

Thanks...

...for all the suggestions. Other than keeping the cap off and lifting the drivers front side of the car are there any other methods that I can use to make sure all the air escapes?

hllon4whls - You said, "you are probably being hyper sensitive to the gauge. I doubt you ever stared at it so intently before you changed the pump." I have to disagree because I am very meticulous and I always want to know what is going on with the engine so I monitor the temp, volts, oil pressure and fuel at least a dozen times per trip. That is every time I drive the car. I have noticed that the oil pressure and temp seem to be higher since the pump and t-stat swap.

I will see about purchasing at least a temp gauge from a local speed shop today. What is the best type? Electrical or mechanical?

 

[HISSIN50]

depends upon personal preference and where you are gonna mount it (logistics). i prefer mechanical gauges personally. i like the full sweep (which does come with some high end [$$] gauges i cant afford) but i also like not having the electrical system have any effect on the readings.

it can be a bit of a pain to run a mech temp gauge to a pillar (goes back to the logistics i mentioned). and many folks dont like having an oil line in the car (which if it leaks or breaks, is bad news).

good luck.

 

[liv2ride]

depends upon personal preference and where you are gonna mount it (logistics). i prefer mechanical gauges personally. i like the full sweep (which does come with some high end [$$] gauges i cant afford) but i also like not having the electrical system have any effect on the readings.

it can be a bit of a pain to run a mech temp gauge to a pillar (goes back to the logistics i mentioned). and many folks dont like having an oil line in the car (which if it leaks or breaks, is bad news).

good luck.

This morning I went out to the garage to look at the radiator level and found that it was to the top. I also glanced at the level in the over flow bottle and it was in the middle of the high and low lines. So, I decided to take your idea of jacking up the drivers front side to make the filler neck higher than the rest of the system and ran the car until it got up to running temp (radiator level dropped some) then I pinched off the over flow hose and filled the radiator with distilled water to take up every possible space that air could remain then quickly placed the cap back on.

I think I have the problem resolved. I drove the car again today during the day with temp outside near 80*. I tried driving with and without the headlights on and with A/C running and without. The temp remained a few needle widths beneath the middle line but once it went up to between the middle line and the line above it but it quickly returned to the below middle position where it remained.

Now, what size gauge is recommended to place them in the area just beneath the stock stereo? I was thinking 2". That should be a good location for a mechanical gauge for cooling temp and oil pressure. I really like the brackets that use the air vent but I do not want to obstruct the flow for the A/C because it gets too damn hot here.

Mahalo and Aloha.

Scot

 

[HISSIN50]

Now, what size gauge is recommended to place them in the area just beneath the stock stereo? I was thinking 2". That should be a good location for a mechanical gauge for cooling temp and oil pressure. I really like the brackets that use the air vent but I do not want to obstruct the flow for the A/C because it gets too damn hot here.

Mahalo and Aloha.

Scot

Scot, sorry i forgot earlier to mention that some like to pull the ECT sensor to help bleed air. some also like to have the heater run at full bore while bleeding.

in a closed system like ours, it should bleed itself eventually. of course, if the system is not holding decent pressure (leak, etc), the effective boiling point is lowered considerably, which can equate to hotter running.

in all probability you will need a 2 inch gauge. i would get the stereo plate first - just to be sure. hate to get the wrong size gauges.

Aloha, the Haole.

 

[liv2ride]

Scot, sorry i forgot earlier to mention that some like to pull the ECT sensor to help bleed air. some also like to have the heater run at full bore while bleeding.

in a closed system like ours, it should bleed itself eventually. of course, if the system is not holding decent pressure (leak, etc), the effective boiling point is lowered considerably, which can equate to hotter running.

in all probability you will need a 2 inch gauge. i would get the stereo plate first - just to be sure. hate to get the wrong size gauges.

Aloha, the Haole.

I never thought to remove the ECT, what a dummy I am - haha. Ah, well the heater is not an option because I live in Hawaii and it has been removed since the core leak. I don't think that a leak in the system is even a possibility because I am so meticulous.

I will measure the area closely and perhaps fabricate a mounting plate to make it look nice.

Thanks again for all of your valuable input. It's nice to know that many people frequent this board.

BTW, I too am Haole.

Aloha

 

[2002BLGT]

yall are forgetting one thing with this car , its only got 43K miles on it , its been sitting alot , the fluid in the clutch fan has probably leaked out , and its likely the car still has the original radiator cap on it which has age on it and its probably not holding the correct pressure on the system .....IMO....replace the clutch fan and radiator cap and your problems will be solved

 

[HISSIN50]

yall are forgetting one thing with this car , its only got 43K miles on it , its been sitting alot , the fluid in the clutch fan has probably leaked out , and its likely the car still has the original radiator cap on it which has age on it and its probably not holding the correct pressure on the system .....IMO....replace the clutch fan and radiator cap and your problems will be solved

actually i had thought of those. in his first post he said it idled fine and cool (and he had trouble while driving), so i omitted the clutch (i dont know how often they fail). i would assume that their life is more regulated by lifetime rotations and slippage than standing life - many sit around on shelves for some time. the procedure for storing one properly is more important (IMHO) than the clutch. also, the silicone in the clutch's viscous coupling is somewhat viscous - it would take a good seal failure to let it come out.

2002, i agree with those things you said, in general - and you still might be right. i would simply wait to get a real gauge installed before tossing new parts like that at the car (i think your cap idea is a great one! but quality fan clutches are pricey and i would hate to toss money at it w/o knowing the clutch was at fault). i still have a feeling it is a a bit of air that is left in the system or an electrical anomaly (with what he said about the other gauges reading different as well).

 

[87'GTstang]

yall are forgetting one thing with this car , its only got 43K miles on it , its been sitting alot , the fluid in the clutch fan has probably leaked out , and its likely the car still has the original radiator cap on it which has age on it and its probably not holding the correct pressure on the system .....IMO....replace the clutch fan and radiator cap and your problems will be solved

With the presence of the 130 amp 3g alternaotr being mentioned, may as well just use an electric fan conversion instead.........

 

[liv2ride]

actually i had thought of those. in his first post he said it idled fine and cool (and he had trouble while driving), so i omitted the clutch (i dont know how often they fail). i would assume that their life is more regulated by lifetime rotations and slippage than standing life - many sit around on shelves for some time. the procedure for storing one properly is more important (IMHO) than the clutch. also, the silicone in the clutch's viscous coupling is somewhat viscous - it would take a good seal failure to let it come out.

2002, i agree with those things you said, in general - and you still might be right. i would simply wait to get a real gauge installed before tossing new parts like that at the car (i think your cap idea is a great one! but quality fan clutches are pricey and i would hate to toss money at it w/o knowing the clutch was at fault). i still have a feeling it is a a bit of air that is left in the system or an electrical anomaly (with what he said about the other gauges reading different as well).

Damn HISSIN50 you hit it in the head. The cap is brand new - within the last 4-5 months. The fan was tested the old fashion way, the rubber mallet while spinning trick and it never skipped a beat. I think it is good to go at this point but I will still bleed the system once more for good measure.

Thanks again to everyone.

 

[HISSIN50]

Damn HISSIN50 you hit it in the head. The cap is brand new - within the last 4-5 months. The fan was tested the old fashion way, the rubber mallet while spinning trick and it never skipped a beat. I think it is good to go at this point but I will still bleed the system once more for good measure.

Thanks again to everyone.

sounds like a plan to me. keep the thread updated if something changes - you have a captive audience here.

take care and it easy while laying around on the beach.

 

[liv2ride]

sounds like a plan to me. keep the thread updated if something changes - you have a captive audience here.

take care and it easy while laying around on the beach.

Well, I am responding sooner that I would have liked to. Well, here is the update. I once again attempted to drive the car to work this morning, got a little further than last time (about 7 miles) then the temp began to rise as I was pulling a decent size hill on the freeway. The temp climbed to about a needle over the 3/4 mark then I pulled off the freeway thinking I would have to stop. I came to a Stop sign and by time I began to pull away from the sign the temps were back down near the half line.

This evening I check the upper and lower hoses, squeezing them in an attempt to push air around in the system to help get it out. I loosened the clamp on the water pump side of the lower hose to twist it slightly because it was not as round as it could be, in my opinion and I thought that might contribute to this condition. I jacked up the driver’s front of the car, removed the cap and began to bleed the system of air once again. The temp is always between half and the line beneath when idling or driving easy without putting much load on the engine. So once the temp got to that point I did detect a slight drop in coolant level so I pinched off the over flow hose grabbed the throttle linkage and held it steady at about 2k rpm and filled the void in the radiator with more distilled water then quickly put the cap back on while holding the throttle steady then released the throttle. I thought that this time I might be shocked but once again once I left the house I put the car through the paces - revving it out some as I climbed the hill outside my neighborhood and what do you know? Within a mile the temp was up between half and 3/4 (remember that I had warmed the car up to top off coolant) but when I realized the temp I drove easy and the temp returned below half again. I immediately went to my neighbor’s house (he's a mechanic by trade) and asked him to get in. We went for a good ride and I tried to load the engine as much as I could with the evening traffic and was able to get the temp gauge over half but not higher than between half and 3/4. He said that the water pump and thermostat must be good. He suspects that it is either the clutch for the fan or the temp sensor for the gauge because of the different flow coming from the high volume water pump.

So, now I am hoping that I can get away with not having to remove the water pump again but rather purchase a new clutch for the cooling fan. I know we tested the clutch the shade tree way using a rubber mallet once the car was up to running temp and the fan did not skip a beat. I will now end my evening knowing the solution is possibly a mere $20-$30 away rather than 2-3 hours of labor and countless minutes dealing with the parts guys trying to get them to exchange the pump.

I guess I will end this chapter of the novel but will continue once I get the clutch installed and take the care for another drive.

If there are further suggestions I am listening. BTW, I bled the system a total of 5 times. Yes, the cap was off until the t-stat opened and I still allowed the engine to run for about 15 after, adding water to top off the radiator each time.

Aloha

Scot

 

[HISSIN50]

so would you characterize the 'hot' running as occuring at higher speeds (say 30-70 mph)? if so, i would look at a couple things (and if you dont run hot while idling, the fan clutch would not be my first choice). once you reach ~25 mph, the air flow from the car moving is more than the fan puts out. said another way, if one could turn the fan off, doing so at ~25 mph would keep the car running at the same temp - not hotter or cooler).

if overheating is a product of higher revs, i would see if your lower rad hose has a spring in it (you can squeeze the hose when the hose is cold and feel the spring). some folks have had hoses collapse at higher revs.

i cant remember (and am too tired to read) - this is all based on the stock temp gauge, right? if you have a spare mechanical gauge, toss it on there for now (the sender is right behind the dizzy and to the left a little. it has one wire).

i would hate to see you jump through all these hoops 'cause of the stock gauge. also, new senders are 4 bucks at parts stores here on the mainland (so they are probably 10 bucks for you. LOL).

if you were overheating at idle, i would jump on that fan clutch, but it does not seem that is when you are running the hottest. another thing - when one overheats at speed (and is alright in town, idling, etc) that can suggest the radiator is clogged or not transferring heat across the coil.
a rad shop can flow test it.

[takes a breath] those are the points i can think of for now.

good luck Scot.

 

[liv2ride]

so would you characterize the 'hot' running as occuring at higher speeds (say 30-70 mph)? if so, i would look at a couple things (and if you dont run hot while idling, the fan clutch would not be my first choice). once you reach ~25 mph, the air flow from the car moving is more than the fan puts out. said another way, if one could turn the fan off, doing so at ~25 mph would keep the car running at the same temp - not hotter or cooler).

if overheating is a product of higher revs, i would see if your lower rad hose has a spring in it (you can squeeze the hose when the hose is cold and feel the spring). some folks have had hoses collapse at higher revs.

i cant remember (and am too tired to read) - this is all based on the stock temp gauge, right? if you have a spare mechanical gauge, toss it on there for now (the sender is right behind the dizzy and to the left a little. it has one wire).

i would hate to see you jump through all these hoops 'cause of the stock gauge. also, new senders are 4 bucks at parts stores here on the mainland (so they are probably 10 bucks for you. LOL).

if you were overheating at idle, i would jump on that fan clutch, but it does not seem that is when you are running the hottest. another thing - when one overheats at speed (and is alright in town, idling, etc) that can suggest the radiator is clogged or not transferring heat across the coil.
a rad shop can flow test it.

[takes a breath] those are the points i can think of for now.

good luck Scot.

I don't have much time to write now but I can do a quick one. The temp rises consistently after placing a load on the engine. Driving even 80mph it appears to be fine as long as I am not getting there quickly. With the car parked in the garage w/ me under the hood I manually revved the engine and watched the lower hose and nothing unusual appears to be happening with the hose.

Once again, the car tends to heat up when climbing a hill swiftly (lot of throttle, low rpm) no matter what speed ex. 35 mph 4th gear or when accelerating hard. The temp takes about 30 - 45 seconds to start climbing. Once the temp rises to whatever it peaks at it returns to the half mark or lower within approximately 1 - 2 minutes.

This is frustrating.

Thanks HISSIN50.

 

[liv2ride]

Well finally.

Well, since the other posts I have made on this topic I will keep this update brief.

1-I bought a new temp sender and it seemed to help, at least slow the temp rising. Car still never overheats but the stock gauge goes up to about the 3/4 but immediately cools to below 1/2.

2-I bought coolant systems cleaner that you can actually leave in, doesn't require flushing the system. After 15 hours the system should be thoroughly cleaned. I will drain and refill the system after a month or so to get the junk out.

3-I bought and installed Auto Gauges coolant temp and oil pressure. I took the car for a hard drive last night trying to load the engine to see how hot she would get and she never exceeded about 182-183.

Case closed. Thanks again for all of your support.

Aloha

Scot