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Cooling Problems/questions After New Water Pump


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Hey guys,

About 6 months ago my water pump gasket started leaking.

I ordered a brand new Nissan GTST pump, belt and gasket. Gave it to my mechanic as I was not brave enough to take the timing belt off and lack of time etc....

Anyway, he put it all back on but there have been a few things I have noticed and I am not sure if it is a result of things he's done or I just havent noticed it before:

1. As soon as I got the car back I noticed a slightly different note from the motor running, sounded a little more noisy. - He said thats due to the new water pump belt and it's a little tight so it might make that sound for a while, fair enough, admittedly it has reduced in noise, but not completely, not like it used to, I'm probably just pedantic about my car - nothing to worry about?

2. The car definitely does not run as cool, on the powerfc on cruising on the freeway even in melb's current cool weather, I am sitting on about 81-82, if I boost through a gear and then just roll after that temp instantly goes to about 85-86, when it was hot earlier this year just cruising on the freeway on a 35 degree day it got to about 95-96, never seen it that hot before. to consider though, with the responsiveness of the current turbo, when cruising in 5th on the freeway I am always on boost, and turbo is water cooled so I know that is contributing, but I remember when I had another turbo that was just oil cooled temps would never ever move past 78deg(I get that the turbo itself was hotter, but what about the motor?). I still have the factory clutch fan and shroud, I have never had the current radiator flushed, maybe an idea?

3. I think alot of these issues may still be caused by air bubbles, I have tried to remove the bleed screw mutliple times etc and have had a few odd bubbles come out. I have never noticed it before, but when I drive to work (32kms), then turn car off and sit there for a minute, you can start to hear bubbles of something bubbling away. It sounds like coming from around the back of the block - maybe through my turbo's braided water line - very hard to pin point, but there is definitely bubbles somewhere in there and they sound watery, ie they arent a glug, glug sound but more of a blip blip blip sound. I tried to record it but it's fairly faint and can't get it on an iphone. happens after a decent drive. Do I need to rebleed the system?

Everything else seems fine about the car, oil is nice and dark, no milky bits, boosts well (not when completely heat soaked) and is running normally - the reason I am so concerned about cooling is because it's a GTS+T,so higher compression and it can suffer pretty badly from heatsoak so I would like to keep temps as cool as possible - 78 to max 80 all the time. thoughts? suggestions?

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could have a bit of an air lock in the heater core? could try filling cooling system from heater hose, hard to say about noises, if it's making a different note should check belt is timed properly etc

Edited by WMDC35
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If the base timing (or CAS) wasn't set correctly when the timing belt went back on, retarded timing can cause engine to run hotter than normal.

Best way to bleed the system is with heater on full, cut a 2l coke bottle in half and use something (like duct tape) to seal the radiator cap opening, this ensures it's the absolute highest point (opening the bleed screws or jacking up the front can't hurt either)

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yep as stated about, ensure the heater is on full bore, ensure you run it at a high idle and let the air bleed out

Low 80s is fine for coolant temps... those figures up around 95 are not so good, air in they system can definatly casue this though so its imperitive u bleed it properly.

as for your turbo always being on song in 5th... are you saying it didnt use to always be this way? if so your cam timing could definatly be out and should be checked

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Cheers guys.

could have a bit of an air lock in the heater core? could try filling cooling system from heater hose, hard to say about noises, if it's making a different note should check belt is timed properly etc

Interesting about heater core, that went about a month before the water pump, I fixed that myself and bled the system and it was fine, i think thats what caused the water pump gasket to go, must have dried out a little. the sound sounds like it is coming from lower down around the water pump though, I did spray some wd on the joint just incase because it is brand new and might be abit stiff

If the base timing (or CAS) wasn't set correctly when the timing belt went back on, retarded timing can cause engine to run hotter than normal.

Best way to bleed the system is with heater on full, cut a 2l coke bottle in half and use something (like duct tape) to seal the radiator cap opening, this ensures it's the absolute highest point (opening the bleed screws or jacking up the front can't hurt either)

I still have the marks he made when he took off the cas and it has lined back up properly. If that was the case surely the car would drive differently though?

Low 80s is fine for coolant temps... those figures up around 95 are not so good, air in they system can definatly casue this though so its imperitive u bleed it properly.

as for your turbo always being on song in 5th... are you saying it didnt use to always be this way? if so your cam timing could definatly be out and should be checked

I know low to mid 80's is ok, but its more that it was lower, why not anymore? I meant with another older turbo that wasent as responsive, so it wouldnt run as hot as it wasent constantly on boost. current one has always been the same, so I know that the boost will increase temps,

Check the timing and try bleeding it more with the heater and all. It takes ages to properly bleed the system doubt mechanic would have spent so long doing it.

Yeh - I think this might be the key, he admitted he spent as long as he could doing it, but said there may still be some air in it and to just remove the bleeder screw until it was a constant stream... i know thats the theory and I have removed the screw multiple times but you end up just about loosing all your coolant doing it, might need to attach a line to that and then let that trickle back into the overflow bottle so I keep it in the system.

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I have a bleeder on my radiator cap, dont know if that would do a better job or not compared to the bleeder on the manifold,

you have a similar setup to me too, interesting how once the GT30 went on, my temps have come down from low 80's to low 70's.

Is the water pump the right one? could the belt be slipping on the pulley?

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The turbo shouldn't be producing ANY boost at highway cruise. I would be checking the cam timing is correct.

And just because the CAS is put back "in the same place" doesn't mean that the base timing is correct. Should always check with a timing light.

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It's obviously not bled properly, as has been stated, and it's very possible that it's not timed right - possibly both cam timing and CAS. if the exhaust cam is a tooth off (heaven forbid) then putting the CAS back to the old mark is effectively not right. Anything of a number of possibilities are possible here.

For my car (R32) we've always had a hell of a time getting it to bleed up. The best way is to do the coke bottle trick, or the proper radiator cap-funnel adaptor, and then run it on the dyno to get it real warm and make sure the thermostat is fully open. Open the bleeder(s) and make sure that they not only flow but are not clogged (the back one on my Neo was clogged to shit and needed a good poking). Heaters on, of course.

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I have a bleeder on my radiator cap, dont know if that would do a better job or not compared to the bleeder on the manifold,

you have a similar setup to me too, interesting how once the GT30 went on, my temps have come down from low 80's to low 70's.

Is the water pump the right one? could the belt be slipping on the pulley?

Yeh, pump is definite replacement, possibility about the slip but how to tell? I have visually inspected it running for about a minute and no sign of reduced speed or vibrations.

The turbo shouldn't be producing ANY boost at highway cruise. I would be checking the cam timing is correct.

And just because the CAS is put back "in the same place" doesn't mean that the base timing is correct. Should always check with a timing light.

ok, will keep in mind. Perhaps I am not describing the boost on highway correctly, I didn't elaborate as I thought it wasn't that relevant.

Turbo is not whistling on cruise - 5th gear, 100kph, ~2800-2900rpms, 0psi, with the way that traffic is in the morning/arvo constant speed ups/slow downs, overtake a car and THEN instant 5-10psi.

Same thing when slowing down to 80kph, need to accelerate back to 100, touch accelerator and instantly get a couple of psi.

As you can imagine this happens alot and this is why I was saying that I believe it may be contributing to extra heat.

It's obviously not bled properly, as has been stated, and it's very possible that it's not timed right - possibly both cam timing and CAS. if the exhaust cam is a tooth off (heaven forbid) then putting the CAS back to the old mark is effectively not right. Anything of a number of possibilities are possible here.

For my car (R32) we've always had a hell of a time getting it to bleed up. The best way is to do the coke bottle trick, or the proper radiator cap-funnel adaptor, and then run it on the dyno to get it real warm and make sure the thermostat is fully open. Open the bleeder(s) and make sure that they not only flow but are not clogged (the back one on my Neo was clogged to shit and needed a good poking). Heaters on, of course.

thanks mate, I am going to try the coke bottle next weekend and as an intermediate option until I can get on a dyno just let it putt away for an hour or so. Atleast that way I can hopefully say right - there are no bubbles, now to look at base timing and cas, process of elimination.

What are thoughts if I open the bleeder and instead of loosing all that coolant I put a line around the bleeder and let that funnel into the coke bottle attached to the radiator and thus it can continue to go around and remove air without loosing all coolant?

Not being a cheap ass, happy to buy more coolant but I end up loosing more then I put in leaving the car going with bleeder open.

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