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MG Midget and Sprite Technical - MORE 1500 Cooling questions!

Simple question: should water not be able to flow any direction through the system as you try to flush it all out? I only ask as when I try doing it via the set-up in the picture, it's completely clogged and wont allow anything to pass. As you can see I have removed the water pump and rad. I want to flush the block and make sure there's no restricted flow. When I removed the block drain all fluid came out cleanly and I could push water though my set up, but when I put the plug back in nada.

My brain is slowly turning to mush with this car!

Chris Elkerton

Also, on the expansion tank, it'll hold 90% pressure, but there's a very faint air leak at the circled hole. Do I need a new cap to make it 100% airtight?


Chris Elkerton

Chris - my car is all in bits so I can't easily check what is plumbed where.

You are connected to the inlet manifold cooling circuit in your picture - I can't recall where that goes next - through the heater matrix ? is there a heater valve in the way ?

If not it may be silted up?
John Barber

Yeah, off the top of my head I think you may not be entering the block there? I think IIRC the inlet cooling pipe you are attached to goes off to the heater and returns through a pipe that runs under the manifold into the pump... so 1 make sure your heater tap is open.

If I were you I would fashion a way of flushing from the bottom up... if you go in via the drain plug then it should come out of the pump...

C L Carter

I tried the valve both open and closed and it didn't make a difference. I just assumed the whole system was one bog loop and no matter where I attached a hose, water would work it's way through...
Chris Elkerton

Could be the valve has been closed for a while - if so it can get blocked with silt so when its open it still does pass anything - I would try going in direct to the main coolant circuit and deal with the heater seperately afterwards..
John Barber

ok. Will try that. Thanks...
Chris Elkerton

They do tend to silt up where the pipe goes through the inlet manifold casting - i.e. where you have it connected. The other side of the manifold there will be a short rubber hose, I think connecting to the heater matrix. I would disconnect this and clear through the manifold separately. You don't really want to flush a silty blockage in the manifold through anywhere else, and certainly not into the heater matrix
Guy

So would it make sense in this case to fashion a pipe to go into the engine block (where the drain is) and run water through it that way? Then tackle the manifold / heater matrix pipes all separately and not connected to the whole system?

Thanks again for all the input!

Chris
Chris Elkerton

Chris,
flush forward and back at all points of entry and exist to all all parts of the cooling system and heater and get some wire to scrap crud out at all points as the water can run clear passed the crud

check the seal on that pressure cap, if you're not sure about it replace it

being a Canda car it might have more to it than we're used to dealing with a UK car but here's extracts from my stock notes

check and change if required the thermostat, filler pressure cap, heater valve (and water pump)

also check and replace as required the fan belt and check the fan is clean and secure

as recent new rubber cooling hoses tend to be poor quality you may also want to change your existing rubber hoses set to silicone with rounded-edge clips

· refill with the correct coolant mixture but bear in mind tap water isn’t the best use distilled instead

· follow the refill instructions from the Driver’s Handbook to avoid getting air locks or ‘hotspots’ that could cause overheating of the engine

to get the heater matrix working really well - thoroughly clean out, flush and back flush whilst shaking, gently brush clean the matrix fins and very important renew the seals and foam around the heater matrix and heater box case


A good cooling (and heating) sytem is very important to the car running well
Nigel Atkins

Took inlet manifold off and sure enough, the pipe leading down to the block was completely blocked. Almost fused closed. Back to flushing and cleaning and washing oh my! :)

C
Chris Elkerton

This thread was discussed between 14/05/2012 and 15/05/2012

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