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Post by fortyfiver on Feb 28, 2021 11:28:09 GMT
Hi all
just fitted a Mercedes header tank, fitted a hose from bottom of tank to the U hose via a tee and top of tank to a 90 degree elbow on top of radiator, the problem I’m having is at idle nothing happens but upon reving the tank fills from the top until at idle again when it empties, the pump doesn’t seem to be drawling water down from the tank.Any ideas?
thanks Alan
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Sapphirestag
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Letting your tyres down at the moment. I was also a target of the Fiefdom controlling the SOC forum
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Post by Sapphirestag on Mar 1, 2021 11:06:44 GMT
It would help if you could post some pictures of how you plumbed it in to the existing system.
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Post by fortyfiver on Mar 1, 2021 11:15:51 GMT
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Sapphirestag
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Letting your tyres down at the moment. I was also a target of the Fiefdom controlling the SOC forum
Posts: 129
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Post by Sapphirestag on Mar 1, 2021 11:28:20 GMT
Looking at that, have you got the heater valve open ? have you tested it with the heater valve in both positions? best method really is to just have it as an expansion tank. connect it to the top hose (hot return from the engine) and then the smaller hose to the bleed on the other side of the radiator.
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Sapphirestag
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Letting your tyres down at the moment. I was also a target of the Fiefdom controlling the SOC forum
Posts: 129
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Post by Sapphirestag on Mar 1, 2021 11:34:04 GMT
There is a supplier of an after market tank who suggests people install it in such away that it allows an amount hot coolant to bypass the Radiator. Not a great idea. Some owners have also found this to cause their cars to run hotter and reworked the plumbing to prevent the poorly thought out design and curing the problem. If you think about it, the only reason to fit a different tank is to put a head of water above the water pump and increase the volume of the system slightly as insurance against and coolant loss. So why complicate things. I have the wards set offering which just acts an expansion vessel really.  |
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Post by misterbojangles on Mar 1, 2021 12:03:06 GMT
As Koy has stated on the SOC forum and the same as mine, is to have a spigot put in the rad towards the bottom on the near side, return the modified heater hose to original, connect the bottom hose from the tank to the new spigot and worry no more.
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Post by fortyfiver on Mar 1, 2021 13:19:27 GMT
Put a 2mm restrictor into the top hose and that slowed the filling of the header tank down but still did it slowly, then tried your idea of heater closed and it stopped it completely, heater on again and it started to fill, any ideas? Or is it telling me to only drive it in the summer
Alan
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Sapphirestag
Full Member
Letting your tyres down at the moment. I was also a target of the Fiefdom controlling the SOC forum
Posts: 129
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Post by Sapphirestag on Mar 1, 2021 14:08:33 GMT
Reply deleted due to misunderstanding  |
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Post by fortyfiver on Mar 1, 2021 14:50:38 GMT
Will re plumb eventually but I can’t understand why water going through the heater matrix makes the header tank fill up from the top of the radiator when reved and bypassing the heater matrix doesn’t, perhaps that bottle of whiskey will help me think straight
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Sapphirestag
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Letting your tyres down at the moment. I was also a target of the Fiefdom controlling the SOC forum
Posts: 129
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Post by Sapphirestag on Mar 1, 2021 15:03:05 GMT
Reply deleted due to misunderstanding |
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Sapphirestag
Full Member
Letting your tyres down at the moment. I was also a target of the Fiefdom controlling the SOC forum
Posts: 129
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Post by Sapphirestag on Mar 1, 2021 15:05:24 GMT
You will get a higher return flow through the smaller bleed hose as the revs increase the flow. hence the need for a restriction.
So having re read your post, I'd hazard an educated guess that turning the heater off stops the flow from the return pipe directly back into the water pump and therefor allows the water pump to do a better job of increasing flow through the radiator. It maybe your water pump is not working 100% i.e. the impellor to housing clearance not set properly.
Personally I'd replumb instead of taking the inlet manifold off to check the pump. That's assuming the car was running OK prior to fitting the header tank?
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Post by fortyfiver on Mar 1, 2021 15:33:01 GMT
No it’s filling from the radiator top, thanks for the help Alan
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Post by Flying Farmer on Mar 4, 2021 9:27:09 GMT
I reckon the rapid return flow from the heater is hitting the the return from the header tank head on and actually stopping or reversing it. This is the reason it works when the heater is switched off.
Try putting the header tank return onto the original expansion tank feed which you have probably plugged as I can see a couple of jubilee clips on it.
There is enough pressure differential across the radiator core to generate a slight flow, but not enough to bypass the rad significantly due to the length and bore of the pipe.
I did this on my 1st stag as a temporary job about 7 or 8 years ago and have never needed to change it.
Neil
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Post by fortyfiver on Mar 4, 2021 12:05:40 GMT
Will try that, have to get a new U hose and a reducer 26mm to 8mm, will have to search eBay, have fitted new radiator new hoses, viscous fan and stainless tubes, I thought it would be straight forward ha ha
Thanks Alan
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Sapphirestag
Full Member
Letting your tyres down at the moment. I was also a target of the Fiefdom controlling the SOC forum
Posts: 129
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Post by Sapphirestag on Mar 4, 2021 12:21:27 GMT
Like I said, when I misunderstood your problem and adding to Niels theory. I would put the T piece in so that the heater return goes through the top straight part directly into the water pump and connect the header tank to the stub part. that way the heater return flow has not got to flow through 90 degrees to return to the pump.
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