Rb20det Runs Hot In Winter/ Normal In Summer

[itchymoose]

Getting desperate for ideas!

I have an r32 skyline that runs hot in cold weather and is fine during warm to hot weather! Have had exhausted just about every test known in attempting to diagnose problem! For example when i first got my car back from getting its rb20 stripped down and completely rebuilt. We were still getting some cold overnight temps and when driving it in temps of less than 18c degrees it would warm up very quickly then would climb under whatever conditions to 100c degrees, whether just idling or boosting up.

Then in hot warm to hot weather 19c to 36c degrees it would run a perfectly stable 86c! what the???????

Tests done so far: Sniffer test for colling system for head gasket issues - Result = no prob

Compression test = no prob

pressurised cooling system = no prob

temp test to validate wolf temps and it really is hot(no sender or guage issues)

air/fuel ratio check = no lean spots

not likely to be fan issues (has issues on hwy or town)

Water pump is less than 6 months old (if it were water pump you'd think it'd get hot in summer too)

oil pressure is normal

Desperate for help!

1989 R32

My specs for engine as follows: RB20det silver top

arc front mount i/c

factory r33 turbo running 14.6psi

cp racing dump pipe 3.5 inch system (not quite sure)

rebuilt head

ross forged pistons & rings

custom billet rods

acl race series bearings

balance and blueprint bottom end

linished crank

bore machined .5mm from stock

cometic h/gasket

billet 264 degree 8.5mm lift cams (or 9mm cant find sheet)

440cc gtr injectors

wolf3d vers 4

walbro fuel pump

Please if anyone has some ideas they would be hugely appreciated! Next step is pulling it apart again!

[lachlanw]

do you have a fan shroud ? does your stock thermofan work correctly ? eg it draws a lot of power when car is hot . have you checked thermostat? not that expensive / hard to replace

[itchymoose]

fans work fine, have replaced thermostat too! If fans were an issue i would have thought i'd have had problems in summer with overheating. But it only runs hot in cold air temps like below 18 degrees.

[lachlanw]

fan might be cold and not engaging enough . fmic is blocking most air from flowing through the radiator and making warm air not reach the thermo clutch to turn fan on. if fan thinks its cold ( surrounded by cold air) it wont engage . next time it over heats pop the bonnet and see how much air the fan is actually moving

do you have standard fan or some electric ones

do you have a fan shroud

[itchymoose]

fan might be cold and not engaging enough . fmic is blocking most air from flowing through the radiator and making warm air not reach the thermo clutch to turn fan on. if fan thinks its cold ( surrounded by cold air) it wont engage . next time it over heats pop the bonnet and see how much air the fan is actually moving

do you have standard fan or some electric ones

do you have a fan shroud

Did wonder about the cold tassie air affecting the performance of the clutch fan. yes does have shroud. Tho surely if it was fan related then it would cool down on the highway. Not so. Temp still climbs! And yet on days of above 19 degrees it doesn't play up at all. ?????????????? Got many mechanics down here confused! Really don't want to pull down an engine that tests results are perfect on! Was wondering if waterpumps can fail(less than 5000ks old)???

[itchymoose]

If you hold about 2000 - 2500rpm just parked it will cool down. Less than or more rpm than that and it gets hotter. Doesn't seem to flow water thru radiator properly! Which has been replaced with a big alloy one. So isn't a radiator blockage! Also still same prob with old radiator.

Edited May 25, 2010 by itchymoose

[itchymoose]

Did anyone out there know that an rb20 has an internal thermostat behind the waterpump which directs the flow of water within the block/head? If this is true then i am thinking this could be responsible. As it occassionally had issue during a hot day after having a cold overnight temp. I'm guessing(not being a mechanic) that its possible this was jamming in the cold o/night temps in tassie which caused the cooling system to operate incorrectly. ie water not flowing thru radiator properly. It was explained to me that this internal thermostat was designed to help warm up of the engine in cold temps then as it reachs a certain temp it changes the flow within to use the full cooling system not just recirculate warm water(assist in warm up and drive in winter) in the head/block and manifold!

[itchymoose]

Cant find anything on whats behind waterpump? can anyone verify this story? nissan manuals don't mention anywhere.

[itchymoose]

Cant find anything on whats behind waterpump? can anyone verify this story? nissan manuals don't mention anywhere.

Surely i can't be the first person to experience this problem!!! Any info would be greatly appreciated!

[itchymoose]

I'll be sure to give details on what the issue is so hopefully in future in my experience may help save others thousands of dollars!

[Blood]

I'll be sure to give details on what the issue is so hopefully in future in my experience may help save others thousands of dollars!

look forward to outcome

having heating probs myself...

[itchymoose]

What kind of overheating issues? I'd be surprised if you had the same problem! lol! Could only happen to me! Is currently being completely rebuilt! Again!