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Volvo 940 radiator leaking - what are my options?

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Old Jul 1st, 2020, 17:57   #21
Laird Scooby
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Originally Posted by TonyS9 View Post
I don't see how waterless coolant could "cause" a leak its oily and thicker than waterbased. I do understand how it could cause overheating as it has a lower thermal conductivity than water. I have been there and bought the T-shirt with the 360 B230FT, using the 360 rad.
Initially with waterless coolant, 12psi boost, hot days on the track temperature would rise up to about 3/4 gauge, but not into the red. I plouged on and didn't back off, brakes were a bigger problem lol.
Changed back to water based, temperature in better control but the cap (360 spec lower release than 940) was leaking pressure and there was bubbling in the expansion tank after a session. The 32yo plastic tank was also very pressurised. Decide the 360 parts weren't rated for turbo heat waste.
Changed back to waterless,
After a few mods, removed the cowling, blocking bits on the rad and air directors at the side, track day drilled bumper. The temperature is now normal at full power/topspeed. Can rise up a little in traffic without the cowling though.

So it entirely depends on the cooling, and the 940 has good cooling even with the manual non-AC rad. Even if you run out of capacity an auto/air con rad is huge and an OE fit.

With waterless the lack of pressure is a big benefit and it can goto 180C before boiling. It never needs changed and doesn't corrode the block.

Additionally I use OATs in the 940 for 10yrs or more, without any issues so far, what should I expect and when?
Interesting stuff Tony! Thanks for pointing out exactly why the waterless coolant will cause leaks, the extra thickness is likely to breach a small leak that would contain a tinner liquid at the same pressure by putting strain on the periphery of that leak.
That's why i always advise a course of part-changes on ATF rather than the flushing method.

As for using OAT coolant, i daresay you've rebuilt the engine a few times with new gaskets? They are usually the first to suffer from OAT coolant as most gaskets won't resist the acid. Next, the acid will attack the cast iron block a lot more than ethylene glycol will attack the aluminium head.

Additionally, most people won't flush the system properly when changing coolant, even if they think they have. Refilling a previous ethylene glycol system with OAT will cause the formation of silicone plugs because the acid will cause the silicates present in EG to precipitate out of suspension and form a gel which then blocks various waterways inside the block, head and anywhere else.

Setting aside the fact OAT will attack the block and potentially the gaskets in a 940, the fact most people won't strip, clean and dry every cooling component in the system before changing to it or at the very least, flush it forwards, backwards and then flush it again to ensure all the EG is removed, it's safer to simply say don't use it. Factor in the damage the acid in OAT will cause to the cast iron block and it's a case of don't use it.


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Old Yesterday, 10:21   #22
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I changed the 940 HG maybe 15+yrs ago after I diluted out the coolant with water, due to a leaky rad, probably used oats then, it's all you can get in Halfords I think. Does leak a little around the rubber seal to the water pump. Might do a wee refresh on it check bearings mainly, now it's a bit rough and past 200k.

The 360 has lost some compression in 1 cyl but I think that was down to running too much boost on STD mgt. Currently stripping.
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Old Today, 12:29   #23
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I did a full cooling system overhaul on my 940 this January. Probably one of the easier jobs to do. I replaced all the rubber hoses in the engine bay with genuine Volvo ones, thermostat with 82' genuine volvo, water pump with SKF one off ebay, radiator with Nissens one. Seals and gaskets from Volvo and new stainless steel jubilee clips all round. New expansion tank and cap too from Volvo, genuine volvo coolant as well.

I flushed a good 10 loads through the system and back flushed through the heater core and block etc. A lot of grim gunk came out of that as I don't think it had been done in a long, long time! I had a pretty serious leak as well which I couldn't pinpoint, turned out to be the oil cooler hoses. They looked good outwardly but actually they were completely destroyed and split open once you applied pressure to them (think chinese finger trap), it explained why the system would leak enormously when filled up but then stop and never really go down beyond a certain level.

It does look like these parts are being run down stock wise though! My radiator was under 60 when I bought it and I see they are up to 100 now on ebay. Also all the rubber hoses were still in stock but were special order from the "Volvo Classic Parts" warehouse in Sweden so took a while to arrive. They were all top quality, genuine hoses made in Sweden or Poland and were Codan branded for the most part. I got all the genuine bits from FRF in Swansea and was under 200 delivered for everything!

It's still such a novelty to open the bonnet and see the lovely blue green coolant and that the level hasn't changed since I last looked!

Please PM if you know of any black 940s being broken! I'm really keen for a driver's door and both front wings! Paint code 19-23
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