Coolant leak - from where?

furbern · November 4, 2018, 12:53

Hi, I have just changed the oil on my MR2, but I noticed about half a dozen drops of coolant on the under tray before I took it off. When I look there is a drip on one of the a/c pump hoses. So I am wondering where it is coming from. Any suggestions? I thought maybe thermostat housing. Are there any other possible candidates? The timing case looks dry.

Carolyn · November 4, 2018, 18:38

The most common leak in that area is a water pump bearing (which will tend to fling it around the area). BUT. There's the oil cooler/heater unit just above the oil filter that has two hoses connected to it. AND there's the main return hose from the radiator to the thermostat housing.

Up on stands, lie on your back with flashlight and have a good peek around.

When I had a water pump leak I found drops on the edge of the sump...

furbern · November 4, 2018, 22:17

Thanks for the response. It wasn't flung around, but the undertray was sopping. I think your suggestion is good, but I might leave the undertray off, and back it up onto ramps to catch it fresh. I am thinking what is the most awkward thing, ah yes thermostat!

Optimus prime · November 5, 2018, 09:00

I have the exact same problem which I discovered yesterday. I also noticed recently that the coolant level in the reservoir tank has become sporadic reading high and low, my theory is the water pump is letting in air causing this problem.
As a very quick 5 min diagnostics session after pulling into the driveway i thought i heard a cyclic compression noise (with engine on) which could also indicate a water pump failure.

Just have a look on ECP and they cost about £30 and new drive belt is about the same.

has anyone had experience with replacing these? it looks really tight in there.

Carolyn · November 5, 2018, 09:09

It is really tight in there. Get the canister out of your way. A couple of the bolts are pretty much done by 'feel'. The new pump will be a handy guide to where they all are.

The bolts are not all the same length, so make a note (diagram) of where they go.

Make sure you clean out the groove in the timing cover that takes the O ring. I use a spot of grease to hold the O ring in place. It tends to just drop out otherwise.

Optimus prime · November 5, 2018, 09:11

thanks for this, were you able to do all the work from the top?

Carolyn · November 5, 2018, 09:23

Yes. Small hands!

Seriously, it can be done from the top with big hands too. It just requires patience.

I've done a few, and it's still a bit of a pig.

Optimus prime · November 5, 2018, 09:27

This makes me happy! living on the top floor of a flat means it's a PITA dragging the stands and jack to the car.

I have to admit i've never done a water pump before. I've replaced suspension, changed a gearbox and replaced a clutch so i'm capable. doing work is all in the prep... beyond the o-ring I assume there's a main gasket around the pump?

I just need to get a shopping list together, if you give me a helping hand that would be awesome!

Thank you

Carolyn · November 5, 2018, 09:48

No other gasket. Just the O ring, which should come with the pump.

Nothing else required.

Just make sure surfaces are clean.

Optimus prime · November 5, 2018, 11:22

you make it sound easy... i'll try and report back after I've given it a go.

Thank you for your help

Optimus prime · November 9, 2018, 14:24

I can confirm, it's rather tight in there. Great to have a small ratchet available. Good news is that changing the pump fixed the problem.
Thanks for your help!

furbern · November 19, 2018, 09:53

Well I admit I have had a bit a delay since the first posting, suffice to say the LandRover has now passed its MOT, so I'm back on the MR2. This last weekend I idled it till it was as warm as it would go, having jacked it up, removed the undertray, and topped up the header tank. Did anything leak ? No!!!! So I took it out for a drive, just to clear out the spiders that had roosted in the exhaust the last couple of weeks and try and get it a bit warmer, came back and it was creaking very satisfactorily as it cooled. Was there a leak? Noooo!!! Incidentally no sign of the fan coming on, or the gauge getting beyond the mid point. So I am rather puzzled.I am going to mix up some coolant and carry a can of it in the footwell and see if I can get it to repeat at some point. I think it's coming from behind the a/c pump, but you can't run it with the a/c pump removed..... I have tried a borescope up there and still can't see any pink stains.

It's Ok, I'm not expecting anything more than sympathy really.