Weird fan issue - has anyone tried aftermarket rad fans?

[auzzam]

Has anyone tried them? Is there a noticeable difference?

My stock fans seem to only work whilst driving, when idle they don't kick in and the temperature will steadily climb (and overheat if I don't manually power the fans)

Not sure if it's the radiator fan switch which was recently changed, this obviously does its job whilst the car is moving as I can see the fans turn on and off periodically.

Will my fans over heat if I leave them switched on all the time? In which case are after market fans better for the job?

Thanks

[Bear87]

I had the same problem with overheating at idle on my old n/a. We came to the conclusion that there was still air in the system and the air sat infront of the sensor and the fans didnt know when to kick in. When driving the pump was pushing coolent around more sufficiently and the fans would come on.
Bleeding the mr2 coolent system is frankly a pig of a job. Go by the Big Green Book for where all the bleed nipples etc are. Most owners find jacking the back of the car up helps.
Took us 4 attempts before we got it right.
The factory fans are up to the job when the system is bleed correctly but its probably not ideal the run them full time.

[auzzam]

Thanks will give this a try - glad to hear it's not just me experiencing this

Another question would the engine lid fans go someway to help keep the temps down - especially on track days?

Seems a cheap upgrade ... Just wondering it it's actually useful

[Bear87]

Not 100% sure. Its an upgrade that lots of people do. Seen everything from a single fan in original lid to duel fans with a purpose made shroud. I cant see it being a bad thing to do especially for track days. After all na cars have a fan where the intercooler lives on the turbo cars and either draws cool air in or pushes heat out of the side vents (cant remember which way it worked)

[auzzam]

Tried to bleed it and saw quiet a few air bubbles,

Problem still exists and will continue raising in temp even if the fans are manually switched on (only at idle). The moment I hold the revs at 3,000 the temp drops almost immediately.

Do you think this could be a failing water pump? Or shall I keep trying to bleed it more?

[Bear87]

Mmm tricky one it could be a failing water pump or could still be air in the system. Did you bleed from the two pipes under the tray by the fuel tank and in the frunk at the matrix and at the radiator? Also did you have your heater in the hot position to allow flow through the heater matrix?
I would defo try another bleed. At least its basicly free unlike a water pump!

[auzzam]

Just bled it from the two in the trunk, as that's what the mrcontrols was showing as the bleed points.

The others I believe were drain points for the coolant, I'll give it another go tomorrow as the water pump isnt that old (had a recent cam belt change)

Really weird that it cools down as soon as I rev the car definitely points towards a circulation issue.

Hopefully get this fixed soon have a track day booked in a few weeks (although the car will always be moving so shouldn't be too big an issue)

[Bear87]

By reving the car you are moving coolant around the system. The air is likely sitting infront if the coolant temp sensor in the coolant tree as it is one of the highest points in the engine. By reving it the air is replaced by the coolant. Make sure your expansion bottle (dont think thats its name) is between the min and max mark too. I will look for the bleed proceedure and try and post a link for you

[Bear87]

https://midshiprunabout.org/mk2/mr2-coo ... -bleeding/
http://mr2.ie/mr2/bgb/mk2/mechanical/co ... ystem.html

Hope these will help you out!

[Gullzter]

I've got aftermarket fans on my radiator, they very rarely come on at idle, same with stock fans, can't say I've noticed them coming on at idle. I'd say nothing to worry about as the engine shouldn't really be overheating at idle unless you have an issue.

Engine fan kit I noticed made a huge difference, at least checking by hand, my f40 lid traps a lot of heat and I can actually feel it through the cabin firewall so I'd recommend the engine bay fan kit

If you have trapped air, bleed all you valves, (radiator, coolant pipes under car, and block) then once it's only liquid coming out and no air and you can't put any more in, close all the valves and start engine up til it gets warm/hot, let it cool down for 15/20mins then check if it needs topped up, keep repeating til it requires none then take it a blast for 10mins then leave it half an hour and check if it needs topped up again, the air will rise to the filler cap as that's the highest point of the cooling system