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geordie40

Another Super Spec cooling question

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Im after a little bit of help from fellow super spec owners (or previous owners), Im probably going to change the large SD1 rad for an aluminium Polo type rad (info already received from Deano) but Im also trying to loose some of the hoses that seem to be for the original heaters in the Rover. I know I can loose (block off) the one that runs across the top of the engine but there are a couple more that im sure are to do with the heater system.

If you look at photos ive included 

The 1st picture is a small hose that comes from thermostat housing into the expansion bottle.

The 2nd and 3rd pics the hose comes from a "T" piece in the bottom rad hose and loops to the thermostat housing.

 

Can I just block these off?

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Edited by geordie40

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You can’t just block off the top hose.  I tried that and found the engine needed the fan to be running permanently.

i described what AndyW did to his cooling system top pipe in the 2nd Newsletter I sent out to Superspec owners, did you not read it ?  I’ll leave it him to describe which of the other hoses need changing.

Edited by alanrichey

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Hi Alan

Just re read the stuff that was sent out in newsletter 2 and It sort of makes sense, its just that dean has changed his red for the one im currently looking at and he has done away with the pipe across the engine to the bottom of expansion tank.

Correct me if im wrong but looking at the rover manual the 3 pipes from the thermostat housing 1 is to the rad, 1 to the expansion tank and 1 is the outlet to the non exsistant heater with the return coming back to the bottom hose so connecting the heater supply and return shouldnt be a problem ?

 

Looking at this image of a super spec that was up for sale a year or so ago they seem to have done away with expansion tank and it looks like they have a heater as both pipes disapear into the car.

Maybe something to experiment with?

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Yes, the important thing is that the heater return should not go to the top of the rad as in the original design, it should go to the bottom.

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You are correct that the 3 pipes off the thermostat housing are for top hose to rad, metal rail over exhaust to feed the heater and expansion bottle (your 3rd photo), and the small hose is for expansion and air bleed back to the expansion bottle (your 1st photo).  

In the original plumbing for my Superspec, the heater return pipe was tee'd from the bottom of the expansion bottle, and went back across the top of the engine to the top of the radiator. I did away with this pipe and instead plumbed the return into the bottom hose near the waterpump. This means you are not circulating the whole of the cold radiator during engine warmup. My car now warms up in less than half the time.

You need to have 2 circuits in the cooling system, which are switched by the thermostat:
- main loop, large capacity, large bore hoses, from top of engine and thermostat through the radiator and back into the water pump. This is for main engine cooling.
- secondary loop, small capacity, small bore hoses, also from top of engine and thermostat and returning back into the water pump. This is for quick engine warmup when the thermostat is closed, and also feeds the heater.

If you don't have a heater (I don't) you should connect the heater feed and return hoses to make a small loop back into the bottom hose to bypass the radiator and give you quicker engine warmup.

In the photo of the blue Rover engine it looks like they have changed the radiator and also done away with the expansion bottle. The top tank on the radiator allows for expansion, and the rad cap looks to have an overflow hose either to a catch bottle or venting to the ground. I guess that's another way of doing it, but I'd still prefer to have a proper expansion bottle for the pressurised coolant system.

Also they seem to have plumbed the heater return into the air bleed on top of the thermostat housing. That doesn't look right to me - it should feed back into the waterpump intake.

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This is how I re-plumbed my coolant system.

 

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What should the running temp be as now I have it running properly I was t to make sure it's right. I currently have the thermostat for the fan set at 90. 

 

Is that too high or just right?

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Sounds about right Dean.  I've got an 88 degree water thermostat and the engine generally runs around 82 - 92 when warmed up. I've got my fan thermostat set to kick in at about 92, which it only does when stationary or in slow traffic.

 

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That's good. I did put a blanking plate over the hole at the front during winter and need to take it off now it's getting a bit warmer. That should also help it cool, but sat in traffic it did go up to 98ish. I think mainly due to the plate being in place

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Was going to ask what peoples fans are set to cut in at.

Andy 1 last thing, from your diagram you have the hose from the bottom of the expansion bottle connecting to the "T" piece, is this nessecerry or can it just be blanked off as I think Dean just fitted an end stop on his (correct me if I'm wrong Dean)

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If it's the branch that goes to the hose that ran across the top of the engine to the rad, then yes. That one I put a stop on it and it's not caused an issue

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You need to have a feed from the bottom of the expansion bottle back into the cooling system. That allows the system to refill when it cools. The small diameter pipes off the side of the bottle are really only there to bleed air out the system.

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As I said before, I tried removing the top line and the fan ran permanently to keep the engine cool.  So in my car that extra circulation is necessary.   Easy enough to test yours and see if it is needed.   Just for info I am using an 88C thermostat and a 95C fan switch, which works well.

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Hi Alan i was just redoing my system when this topic came up, reading your response can i take it that you tried the method Andy used and it didnt work on your engine

2 hours ago, alanrichey said:

As I said before, I tried removing the top line and the fan ran permanently to keep the engine cool.  So in my car that extra circulation is necessary.   Easy enough to test yours and see if it is needed.   Just for info I am using an 88C thermostat and a 95C fan switch, which works well.

 

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