1998 GT Cooling Issues

[reivaxtorres]

ok, i installed the PI heads this past weekend and everything was going great, still is actually, but now im having a slight cooling/overheating problem when i push my car.

with the NPI heads, i used to be able to hold the car at 5-6k rpms for extended periods of time, usually staying within 4-6k rpms for about 9 or 10 miles and the temp gauge always stayed between the "O" and the "R" of "NORMAL". last night i went out as well and tried repeating the same stuff, except that now the temp gauge spiked up to between the "A" and "L" of "NORMAL" after about 7 miles or so, once i backed off the rpms and kept driving it for about a minute or less, the gauge returned to the middle of the "R". and now i have a few questions:

1) how hot is too hot?
2) i know the PI heads increase compression ratio and thus makes the car run hotter (higher cylinder temps) especially at high rpms, so could this be the cause of the spike?
3) the water pump, as far as i can tell, is still the original one and is still working perfectly. never had issues with it before and i dont think its going bad, might just not be able to keep up with the demand tho. IF i have to replace it, what is a good upgrade to go with? and no, i wont do electric, too many things can go wrong with that. ive been looking at the steeda and the FRPP waterpumps, as well as the 99-04 water pumps (supposed to be improved and offer better cooling). which one would you guys recomend/have used before?
4) probably the more important of my questions, how do you check to see if there are any air pockets in the cooling system? on saturday, i had to refill the coolant overflow tank because of an airpocket that surfaced after about 200-300 miles of driving.
5) when the t-stat opens, why does it not use the coolant in the overflow tank? when i refilled it, i had to refill it with water, thinking it would mix in with the coolant that was already in the system, yet the water is still in the tank.
6) is tap water ok to use in the cooling system, or should i used distilled water/filtered water?


i know its a lot of questions, but anyhelp would be great. plan on taking the car to a road course towards the end of october, so i would like to get this resolved sooner than later. other than that its not real worry for me as during normal driving the car doesnt over heat or anything, it stays pretty much on the "R", just when i abuse it.

FWIW:
- i have ud pullies on my car but its never been an issue. cant re-use the stock ones because the crank one fell apart.
- water pump, as far as i can tell, is still the original one. almost 159k miles.
- t-stat is probably about 30k-45k miles old. replaced it because i was going to be replacing the coolant hose, so i figured id might as well do it.
- using 5-30 synthetic blend right now for the engine oil, i know it uses the oil as another method of helping cool the engine, would this have anything to do with it? i usually use 5-30 full synthetic oil. (was going to drop down to 5-20).

thanks again,
xavier

(ps. sorry for the long post)

 

[Jrgunn5150]

The reason for it not mixing would seem to be your thermostat not opening... The only thing I can think of, and I have had bad one's out of the box before if you just recently changed it.

above 225-ish would be too hot, and I would even try to sustain it there for long.

Even after a swap, you shouldn't get that hot and climbing..

For a decent upgrade, I used a Cobra pump, suposedly a better cooling unit, honestly couldn't tell you. It works, didn't seem to lower temps or anything though.

Are you running premium gas in it? Another thing I am thinking of, maybe it is slightly pinging/knocking and you can't hear it. This would cause it to build quite a bit of heat.

 

[reivaxtorres]

The reason for it not mixing would seem to be your thermostat not opening... The only thing I can think of, and I have had bad one's out of the box before if you just recently changed it.

above 225-ish would be too hot, and I would even try to sustain it there for long.

Even after a swap, you shouldn't get that hot and climbing..

For a decent upgrade, I used a Cobra pump, suposedly a better cooling unit, honestly couldn't tell you. It works, didn't seem to lower temps or anything though.

Are you running premium gas in it? Another thing I am thinking of, maybe it is slightly pinging/knocking and you can't hear it. This would cause it to build quite a bit of heat.

interesting. is the low and high readings on the stock gauge? (i mean what letters/area of the gauge relates to what temp?)

i think ill swap out the t-stat just to be sure, but i know it opened when i did the head swap because i filled the tank, left the cap off, turned on the car and let it sit for awhile, then i heard it open and saw all the coolant from the tank disappear pretty damn quick. filled it up and thought everything was fine. like i said tho, ill replace it just for good measure in the next few weeks. if the t-stat doesnt open tho, how does the coolant in the block/heads/intake cool off, since its not moving thru the radiator?

i thought the 2v and 4v 4.6L water pumps were the same? just either longer or shorter, but ill look into this. i know the 03/04 cobra uses the same pump as the 96-01 GT does.

and yes, im running 91 octane on the stock tune. had been running it for about 2 tanks before i did the swap, and then i had to fill it up when i was done with the swap.


like i said tho, driving it around normally, it doesnt move beyond the "R" of normal, its only when im pushing it really hard that it moves past the "A" and into the "L" territory.

 

[Jrgunn5150]

Well, i have a Autometer temp gauge, my stock one died on me, I also have a Autometer oil pressure gauge, so I couldn't tell you the temp to letter ratio.

Yeah, i agree on the T-stat, it should get really hot, really quick if it isn't opening, but that's the only reason I can think of for it to not draw out of the tank. Or some other blockage, but again, it would get really hot. Maybe you have a partial blockage?

Or maybe the sustained running is really the only cause... I really don't drive like that myself, but it seems abnormal to me.

As an aside, I thought 98's had upgraded cooling anyway? As for the water pump, I couldn't tell you. I heard it, didn't really beleive it, but figured it wouldn't hurt, and as far as I can tell, it didn't make a difference.

 

[reivaxtorres]

Well, i have a Autometer temp gauge, my stock one died on me, I also have a Autometer oil pressure gauge, so I couldn't tell you the temp to letter ratio.

damn. i think the end of the line under "normal" is 220, but i really have no idea. ill search around see if anyone has come up with that before

Yeah, i agree on the T-stat, it should get really hot, really quick if it isn't opening, but that's the only reason I can think of for it to not draw out of the tank. Or some other blockage, but again, it would get really hot. Maybe you have a partial blockage?

thats what im being told by Randy (used to be on modulardepot, now you can find him at modularmisfits or AFM). apparently the 99-01 intake manifold gaskets are slightly different that the 02-04 gaskets, difference being that the coolant ports under the crossover on the gasket are smaller on the 02-04 gaskets. when i got mine, i think i got them for a 2002, but its been almost a year so i cant remember. he said they can be enlarged to make them work, so if worst comes to worse, ill try to mess with these before i start replacing parts (except the t-stat)

Or maybe the sustained running is really the only cause... I really don't drive like that myself, but it seems abnormal to me.

hahaha, to most it does. they cant understand why i do it either, but its fun. (hint, if you want to, go on youtube and look up "GMR touge" to see what it is i do on rare occasions, and i dont go as fast as those guys in the videos do either). as for it being the sustained running, like i said with the NPI heads i had no problem, but then again i wasnt near the CR im at now. i honestly thought it was the water pump not being able to keep up with the engine, which leads me to think that its the gasket issue i mentioned above

As an aside, I thought 98's had upgraded cooling anyway? As for the water pump, I couldn't tell you. I heard it, didn't really beleive it, but figured it wouldn't hurt, and as far as I can tell, it didn't make a difference.

i dont think we did, the only thing different between the 4.6L cooling systems on n/a mustangs is that in 1996, it had a smaller radiator that wasnt effective, so they had to install a better one, which is the one that 97-04 got. mid 01-04 had pump with a longer snout, except for the 03/04 cobra which had the same one i have. at least this is what im picking up thus far today from looking everything up.



thanks for your input so far, on a side note, are you going to be going to GTR anytime soon?

 

[Jrgunn5150]

Yeah I'm going to be making a call in about two weeks to set up an apointment, my little work project is drawing to a close finally.

It's not the sustained RPM that's abnormal, it's the temp rise. There's no reason for it with the swap. I know the CR got bumped, but I neveer noticed it on mine, and I'm at the same C/R even now and still don't really get that.

The gasket may be the culprit, I always just ask for 99 gasket's, for no real reason, but I guess it worked out for me, lol.

 

[reivaxtorres]

Yeah I'm going to be making a call in about two weeks to set up an apointment, my little work project is drawing to a close finally.

It's not the sustained RPM that's abnormal, it's the temp rise. There's no reason for it with the swap. I know the CR got bumped, but I neveer noticed it on mine, and I'm at the same C/R even now and still don't really get that.

The gasket may be the culprit, I always just ask for 99 gasket's, for no real reason, but I guess it worked out for me, lol.

yeah i know, ur lucky. for some reason i kinda liked the number 2002 so i just ordered everything for a 2002 mustang, turns out i shoulda ordered for a 99! but i just went outside to check it the car during lunch, and the water in the overflow tank finally mixed with what was in the block, so im good there. dunno why it wasnt mixing last night, but whatever. from what Randy told me, i can make the ports on the gaskets bigger, which is good because i no longer have to buy new ones (hopefully, unless is screw something up), but the manifold has to come off, which isnt that hard, but damnit i gotta take off the strut brace too. its a PITA to remove because of the location of the 2 firewall bolts. (steeda bar)

 

[Jrgunn5150]

Yeah, maybe it's really the same and you can just pop out the blocked off portion? Anywho, you should be pretty well versed in pooping that sucker on and off by now, lol.

 

[realitygt]

i used to be able to hold the car at 5-6k rpms for extended periods of time, usually staying within 4-6k rpms for about 9 or 10 miles

what are u doing that causes you to keep it at 5grand for 9 or 10 MILES?

 

[Jrgunn5150]

Running down a twisty mountain road, it looks like fun too, lol.

The closest thing I got here is Ortega Highway, and it's usually too crowded to enjoy.

 

[reivaxtorres]

i used to be able to hold the car at 5-6k rpms for extended periods of time, usually staying within 4-6k rpms for about 9 or 10 miles

what are u doing that causes you to keep it at 5grand for 9 or 10 MILES?

Running down a twisty mountain road, it looks like fun too, lol.

The closest thing I got here is Ortega Highway, and it's usually too crowded to enjoy.

yup, its loads of fun. i was actually going to record it last night, but i forgot the zip ties i was going to use to hold the camera to the pony on the grill, so i didnt record it. i was on Ortega a few months back, its fun as well, but its too long for touge driving if you ask me, it would take too long to learn the road, and like you said its always crowded. Ortega is nice to just sit back, relax, and enjoy the cruise. GMR is better suited for touge :dancing6:

 

[reivaxtorres]

Yeah, maybe it's really the same and you can just pop out the blocked off portion? Anywho, you should be pretty well versed in pooping that sucker on and off by now, lol.

yup, sure am. i usually take off the hood too, but that takes like 5 minutes and saves me about 20 minutes and tons of cuz words, hahahaha.

 

[reivaxtorres]

update: its not the gaskets. turns out i did end up getting the 99-01 gaskets, which is a huge plus for me, so i will prob be swapping out the t-stat this weekend and then testing it again sometime next week (as soon as i wash my car and empty out the trunk....). i hope ford has one in stock.

 

[Purple97GT]

I noticed my car does this after the PI longblock swap, too. At the end of the 1/4 mile at Beech Bend in June, my temp gauge was 3/4 the way up after nearly every run (I hot lapped lol), but would cool back down on the return road back to the staging lanes. I also noticed it did this on the interstate in the summer a few times running 70+mph.

My coolant is good, my thermostat is good, no air in the system, etc.

This leads me to believe that maybe the radiator just can't keep it cool with the PI. Maybe we need a bigger radiator, or maybe just running a cooler t-state and program the fan to come on earlier would do it?

I haven't felt my car ping, so I don't think it's going lean.

Is there a way to get the SCT Xcal2 to turn on the fan earlier, or will I have to get Dynospeed to add that in my tune?

With the weather cooling down, I'll probably not work on this until next summer, though. :hammer:

 

[ripper]

You could upgrade your radiator. Ive read in other posts the 96-98 radiators are crap. Bob (droptoppony) has a thread on this. He has done the upgrade and in his post there are some aftermarket radiators listed. I did the PI motor swap. We upgraded the cooling system and my gauge goes just a hair past the N even on the hottest days.

 

[reivaxtorres]

You could upgrade your radiator. Ive read in other posts the 96-98 radiators are crap. Bob (droptoppony) has a thread on this. He has done the upgrade and in his post there are some aftermarket radiators listed. I did the PI motor swap. We upgraded the cooling system and my gauge goes just a hair past the N even on the hottest days.

interesting.....ive always thought the 97-04 GT radiators were the same. ill have to dig into this a little more, but in the mean time im planning my next upgrade to my car, which will be:

Plan A:
1) 180* t-stat
2) Water Wetter

Plan B:
1) New Stock T-stat
2) Hi-Flow Water Pump
3) Coolant Mod Via Intake Manifold
4) 03/04 Cobra Radiator

obviously plan A is cheaper and less labor intesive, but i would prefer to have my car permanetly running cool rather than a quick fix, so if i do find out the 96-98 radiators are crap, ill prob be going with plan B

 

[ripper]

Search for that thread. Or pm Bob. Im almost positive he just swapped out his radiator and problem was solved. If I remember right he used a Fluidyne but im not sure.