Overheating and heater problem

Gatouzze · November 9, 2018, 09:40

Hi all,

Since Tuesday (rainy day), I have an odd issue with my car... while driving the temperature gauge goes up very fast but stops if I rev the car a bit so I check my coolant and I need to put some in as it is below the minimum... if I am correct I need to use the red one right? But that means I have a leak somewhere...

Second issue is the heater... While driving the car gets hot quickly (the gauge though) but I do not have heater except if I start driving faster and I do not mean higher RPM... I use my car to go to work so I mostly get stuck in the London traffic but even going over 3/4000 RPM does not give my heat however I soon as I go on the M23 and reach 45/50 mph the heat starts blowing... I thought the calorstat/thermostat might be stuck but not sure as sometimes it does give my heat quickly...

Any ideas?

Note: I recently installed an AEM air intake however I had the heater problem for a few weeks now (even before changing the air intake...)

dan944 · November 9, 2018, 10:37

I might be wrong but Sounds like an airlock to me. Get her running and check the balled points.

One at the top left of the radiator and one under the frunk plastics for the heater. It's quite easy to see once they're off.

Also to massaging all the coolant pipes that you can get to. Especially the ones at the front of the car.

I also have a tried and tested method of removing air locks which is:
Get the car up to temperature.
Find somewhere without traffic and swerve the car hard from side to side. It tends to move the air somewhat and release any air locks. If you do this with the heating on you can literally feel the heating suddenly get hot as the lock is released.

Hope this helps.

mikek · November 9, 2018, 10:44

+1 for air lock. Massage the heater pipes and bleed the system. This happened to me a couple of years ago. Not happened since I did the above.

james_ly · November 9, 2018, 11:04

Could be a leaky radiator, how much are you having to top up? See if you can see any coolant under the car when idling when up to temp.

Gatouzze · November 9, 2018, 11:15

Thanks guys! I'll try to massage the pipes tomorrow to see if I can get rid of any airlock!

@james_ly I haven't top up yet as I checked the level this morning however I would say around 1 liter to get between max and minimum... I am planning to remove the front bumper tomorrow so I could check if there is any leak to the radiator then!

105e · November 9, 2018, 11:17

If its speed, not revs that encourage warm air to enter the cabin, isnt that the fan not working?

Gatouzze · November 9, 2018, 11:44

@105e sometimes the heating does work just after the car has reached its normal temperature so I don't think (and really hope so) the fan is not working.

Carolyn · November 9, 2018, 13:51

The temperature shooting up so fast indicates the cylinder head is partially dry of coolant, especially when high flow from the water pump (higher revs) makes it drop.

The high points in the system at the back of the car are the cylinder head and the expansion bottle. The high point at the front is the heater.

This means that the coolant level must have dropped.

It's gone somewhere. The radiator is usually the first place to look

1979scotte · November 9, 2018, 14:09

As others have said get the plastics out of the front and have a good look at radiator and pipes.
I've changed rads on both my MR2s and had to swap out some clips to stop leaks.
Radiators are cheap from eBay.

Gatouzze · November 10, 2018, 13:57

So I remove the front bumper and front plastic to check the radiator but couldn't see any leak on the radiator nor the pipes...

I press the pipes while adding more coolant in the system and I roughly top up with 1l...

I will check again the level in a week or so to see if it drops again (hoping it doesn't though)!

Joesson · November 10, 2018, 14:15

@dan944 suggested to check the heater bleed point, but @Gatouzze you didn't mention doing that!
There should be a coiled length of tubing to assist with this procedure lin the vicinity of the heater bleed point.

Gatouzze · November 10, 2018, 15:03

@Joesson and @dangermooser I did try that too and could see the liquid going out with a few air bubbles in the tubing so I left the coolant get out until seeing no air.

After that the heater seems to be working fine s9 the liquid level seems constant so I will try and see if that changes over time!

moredun · November 10, 2018, 15:17

If your friendly with your local garage, ask them to pressure test the cooling system.

I had a hole in my radiator that was so small, only a fine steam "mist" was visible if the temp was up and engine running. Still went through 1L coolant every 100 miles tho (:< >

Joesson · November 10, 2018, 15:19

Perhaps you've now got rid of all the air.
But remember that the coolant level on the 2 is notoriosly inconsistent! worth keeping an eye on the temperature gauge for a while till you regain your confidence in the car.

Carolyn · November 10, 2018, 15:23

The system should pressurise.

The pressure cap on the expansion bottle can cause cause such problems, if it's not sealing properly.

As Moredun suggested check around with it running and up to temp. If it's the cap, you'll hear it.

If it's a pin-hole, you'll spot it.

dan944 · November 10, 2018, 15:36

I'm not sure how normal this is but I've had my car over 8 years and as a rule of thumb I just make sure there's some coolant in the header tank. Even if it seems like it's not enough.
I have never once had an issue other than air locks...and a radiator that blew up. But that was fairly noticeable.

What I'm trying to say is, as long as you keep an eye on the coolant level you'll be fine.