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Cooling Advice?


RPR
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I have a 3.5 V8 of 1982 provenance out of a RRC in my SIII 88". It is mated to a RRC radiator with integral oil cooler a hi-cap engine driven fan that is well shrouded. It is on an 89C thermostat and the thermostat gives no indication of fault. It has always run up quickly to thermostat opening temp but with the hot weather setting in, it is now running up to 100C and slightly above when worked hard and going slow. With the 5.99:1 cumulative effect of diff and hub reduction of the C303 axles, working hard and going slow is pretty much all it does :lol:

It gets inferno like under the bonnet and I think that even the well set up engine fan just can't pull enough cool air through the rad in hot weather to adequately cool. I will give the rad a flush and clean as a first step. I know there are mixed views on electric pusher fans, but that is an obvious second port of call. Third would be means to extract some of the heat from under the bonnet. I am loathe to punch holes in the bonnet etc as that will make it look sort of wannabe 'monster truck' and quite pathetic.

I would welcome thoughts and advice on my dilema.

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Hi Richard.....long time eh!

I originally had a 3.5 with Carbs in the lightweight before going to the 3.9Efi & auto box.

It was running the same tropical rad as the old 2 1/4 petrol for many moons in Saudi (pretty hot there remember).

So long as it's in good condition then it should be able to handle it just fine. It's when you get on the revs that you might notice the needle rising.

The change to 3.9Efi prompted a bigger rad...rangie stylie. Even then in the UAE I think we have it hotter than you guys.

It's worth remembering that the heat build up under the hood is a high presure zone....what ever cool air goes through the grill has to find a way out somewhere. Perhaps wrapping the extractor/header pipes will reduce the under bonnet heat too.

Now you're bimbling at slower speeds then heat build up is bound to to more than when you where travelling across dunes etc. I think you either have to find a better heat disapating rad...aluminium.......or get some sort of breathing going under the hood by ways of venting.

Are you 100% satisfied with the performance of the radiator fan shroud? I made some improvments to my standard V8 one and noticed an immediate improvement. The idea is to get maximum suck through the shroud and then the rad...block off anywhere that can reduce the airflow through the fins.

Everyone has their own draw on the electric 'V's viscous fans. My 4.6Efi runs standard viscous fan with a ali rad and a nice cowling.....no problems with cooling there...even with our 120 degree heat.

I used to run twin 13" Kenlows on the ali rad...I switched back to the stardard viscous set up and noticed much better results.

Regards.

S.

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The 109 runs a full-width but not full-height (due to PAS box) rad based on a Sherpa van but with a very open core, and a pair of fans from an Audi (because they were the right size) and it seems fine with the low gearing of the portals - I would say the engine does a lot of revving but very little in the way of work, I haven't had to push the pedal hard at all yet. I know mine is of superior cubic capacity ;) but I can't imagine yours has it's work cut out either?

An oil cooler could be worth looking at (I know I will be) as they make a surprising difference - a mate had a replacement V8 put into his SV 110 (an emergency vehicle that carried a lot of gear) and they left the oil cooler out :angry: first play day he was overheating like mad and said it had run noticeably hotter since he collected it. <_<

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Thanks Streaky. I think the shroud is pretty good, but I am going to have a go at improving it. I think that may be the ticket. I have decided on working on the shroud and venting some of the heat out via TDI side vents in both wings as per the threads referenced above. I've already got the downpipes wrapped out to the juntion. I remember how much cooling you guys got out of the Saluki by venting, so I am hoping that getting the heat out from under will help.

Fridge - you've got it. The 3.5 doesn't really work hard per se, but it is revving a lot through gearing and that builds up the heat. Even then, it only rarely sees 3200 rpm, so it's not revving very high. The rad I have - with integral oil cooler - is bigger than a stock 3.9 rad from a RRC or Defender so while I will give it a flush, I don't think that's the issue. I may have to look at a separate/dedicated oil cooler.

Thanks for the advice.

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TDi side vents? Why not use Series heater vents - it would be a shame to lose originality :P I'm considering bolting a small car or bike fan to the underside of the bonnet and venting up through the dome of the spare wheel mount, it should be possible to do it without it looking any different as I really don't like the bonnet mushrooms that Kenlowe/Pacet(?) sell.

Just as a thought, I wonder if the revving causes water to go too quickly through the radiator to be cooled properly? Could be worth a measure, wonder if I can rig a spare I/O on the MS to log it B) as I have an electric water pump here that I have been wanting to try out for a while.

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TDi side vents? Why not use Series heater vents - it would be a shame to lose originality

:lol:

I had thought of a similar extractor fan set up but equally despise the bonnet mushrooms and as the Tonka has a "deluxe" bonnet, I don't have the tyre dish. I have a lot of hopes for the venting. We shall see...

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I had thought of a similar extractor fan set up but equally despise the bonnet mushrooms and as the Tonka has a "deluxe" bonnet, I don't have the tyre dish. I have a lot of hopes for the venting. We shall see...

Motorbike fans are cheap from ebay or the scrappy - the rads are ali and catch all the road debris & salt from the front wheel so they disintegrate (or the bike gets crashed) before the fan gives up, I know this because the lodger has just had the joy of paying £100 for a new rad the same size as my oil cooler :D still I got a free fan out of it :lol:

Oh and it also made up my mind not to buy an ali rad - unless you want to try to TIG up wafer-thin corroded ali they're rather tricky to repair (as we discovered) unlike copper where a bit of tin and some solder will get you home and the rad boys will braze it up nicely again for a few quid. Even their pukka repair attempt on the old ali unit was just a bloody good clean and a glorified version of quicksteel and lots of muttering about not being guaranteed :rolleyes:

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wot is wrong with bonnet vents? If done tastefully, then can llok quite fetching, not that I am biased in any way.

If you are not revving too high, then you can fit a smaller diameter water pump pulley - again like I done - to qicken water flow (noone dare mention cavitation :angry: )

I have a 15 inch fan in front and fitted a second msaller 12 inch fan behind raditaor and thae smaller fans does help shift hot air via the vents.

I also have oil coler but oil temp gauge, fitted to sump, has never gone much above 90 degrees - dunno if it is telling the truth though.

post-304-1182961084_thumb.jpg

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