cooling system refresh....

[richrx]

Hi

Ive got the rx tucked away for the winter and im starting on the mechanical work that's needing done. Ive decided to start at the front and work my way back... so the cooling system ...

Initially I want to keep costs down, but dont want to scrimp where parts need replacing.

First sign works needing done was the water was the same colour as rust, and after a long run the rust coloured water was pushed from the expansion tank beside the radiator all over the underside of the bonnet. .. it only done this when the engine was off and it was cooling.

The temp seemed fine on it, with the gauge sitting about 1/3 and never going higher( exept on a 90-95 motorway run, but I slowed down and the gauge never even made the 1/2 way mark), it heated up quickly too.

Also the viscous fan is always stiff and never turns free hot or cold.

So i pulled the fan and when spun its very quiet, no bearing rumble, but oddly intermittently freebthen tight again, I pulled the metal strip from the back but even before I pulled it I could see it was broken, theres a crack in the middle. Once this was off I pulled the small metal button out, it was free and the fan spun freely.

Anyway i decided to crack on and I thought the radiator might need re-cored, but once off it seems fine other than the colour of the "coolant". I think its been rebuilt recently.

I had a look at the thermostat, and the top part, the metal hose looks past its best, but even more worrying is the crud thats blocking it all up. Clearly the coolant can still flow but I fear for the coolant passages in the engine itself.

Ive attached some photos, whats your throughts? Im thinking of pulling the thermostat and water pump too and see the mess there in. I dont think it will be pretty

I am really concerned about the internal water passages, is there an easy fix. I done want to destroy the coolant seals with a chemical cleaner ( if theres such a thing) but clearly theres going to be issues in there




Out with the old coolant. Looks very poor condition. .

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perfectly fine radiator

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[richrx]

Thermostat, works fine, worryingly covered in gunk...

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Hose feom thermostat, poor condition but this is what im worried the internals to the engine and water pump are clogged with...

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[richrx]

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The heat source garage with an open fore! Can't beat it!!

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Thanks

Richard

[TOOL]

Yeah, you'll have a motor full of that stuff.

Here's an example of a relatively good motor:



On the centre iron, on the spark plug side at the bottom you'll see a small bolt. This is the main coolant drain for the block. you can see it here:



Pull the thermostat, pull the heater hose from the rear iron and pull the water pump housing too if you want (make sure you don't lose the washers which keep the housing flush when you bolt it back on). These washers sit on the 2 outlying studs as shown in the next pic (the one I'm holding and the one on the left).



I would do my best to blast water into these orrifices using a garden hose to blow out as much muck as possible. Be warned though, it's like a jelly and is hard to dislodge.

You'll need a new 82 degree thermostat (make sure it's not one of those higher temp ones claiming to suit RX7) and a water pump housing to block gasket. If you take the water pump off the housing, you'll need that one too. All available from Mazda, just quote them the part numbers. Your water pump blades might be gunked up/rusted too causing poor circulation.

The top hose joint always seems to rust quite badly and the ends decay. Hard to find good ones.

Let us know how you get on, and if you need bits, they're sure to be available on here.

[richrx]

Thanks for the reply... keep all the advice coming I think I need it

So is there a fair amount to strip from the engine to get the waterpump housing off? And can I then clear alot of gunk out?

I'm not sure whether to keep the viscous fan ( ideally I want the car original) but not sure if its a risk, possibly overheating the engine if it fails

Rich

[ian65]

Thanks for the reply... keep all the advice coming I think I need it

So is there a fair amount to strip from the engine to get the waterpump housing off? And can I then clear a lot of gunk out?

I'm not sure whether to keep the viscous fan ( ideally I want the car original) but not sure if its a risk, possibly overheating the engine if it fails

Rich

I was talking about the unreliable viscous fans the other day with Keith and he came up with a good idea. I had one on a car and although I've no confidence in them, I didn't want to lose it due to, as you say Rich, originality.
Keiths idea was to fit an electric pusher fan on the other side of the radiator...... it would be hidden by the radiator mounts and top cover but would give peace of mind and cool the engine if the viscous fan didn't. It could be fully automated controlled by a stat or with a manual overide switch in the cockpit. Nice idea and your car still looks totally original when opening the bonnet.
As well as flushing the engine, i'd pull a hose off the heater and fulsh then reverse flush that too until the water runs clear and also do the same with the beehive oil cooler.... it's amazing how much crap with come out.... refill it with a good strong antifreeze mix and you should be good to go. A thorough flush out should keep your temps where they should be.

[Lucky]

I've a couple of viscous fans lying around if yours is knackered and for some reason you want to put one back on, lol. Yours for postage

[codge]

And use only genuine Bluecol - the old blue antifreeze, not the modern red stuff which our engines don't like.

My water comes out blue not rusty....every 2/3 years......ooer, must see the doc.

[myatt1972]

I was looking at these at the restoration show, they were good quality and come in push or pull configuration.
http://www.s-v-c.co.uk/category/fans/

[TOOL]

Thanks for the reply... keep all the advice coming I think I need it

So is there a fair amount to strip from the engine to get the waterpump housing off? And can I then clear alot of gunk out?

Take off the alternator. Take off the fan. Take off the water pump housing. That's about it. It's held on by 4 nuts. Only remove the nuts, not the bolts.If you're undoing bolts, you're about to remove the water pump from the water pump housing.

Personally, I don't see any real advantage in taking the water pump housing off. The block, particularly the lower half is where the issue is. You need to clear that out.