350i Expansion Tanks
Discussion
Hello folk,
So, the 350i has been brought back to life after an almost 2 year hiatus, due in part to Covid 19!!
However, what I need is some pictures of how the 2 expansion tanks are mounted in a 350i - I've botched up a couple of universal brackets, but they look crap.
Can original parts be found/bought, or do I need to try and make something up? Or does anybody have some spares knocking about?
Any ideas, improvement, etc. gratefully received - I'd just like it to look nicer.
Jez.
So, the 350i has been brought back to life after an almost 2 year hiatus, due in part to Covid 19!!
However, what I need is some pictures of how the 2 expansion tanks are mounted in a 350i - I've botched up a couple of universal brackets, but they look crap.
Can original parts be found/bought, or do I need to try and make something up? Or does anybody have some spares knocking about?
Any ideas, improvement, etc. gratefully received - I'd just like it to look nicer.
Jez.
Hello mate, original fitment was a Ford Capri expansion tank plus what looks like (and is) a screenwash bottle, because the Capri tank couldn't cope with the V8s amount of coolant, so TVR thought another tank would do!
The theory being it takes any excess when hot, and returns by capillary action when cooler.
On the plus side, it let's you know when a gasket has blown as it fills both tanks!
The theory being it takes any excess when hot, and returns by capillary action when cooler.
On the plus side, it let's you know when a gasket has blown as it fills both tanks!
Ah, I understand the question now. Main sealed expansion tank is Ford Capri. The overflow bottle is a TR7 screenwash tank. This is not pressurised. The idea is that this has a few inches of water in it. If the expansion tank relieves then it goes into the overflow tank. When it cools down the submerged pipe allows coolant to be drawn back into the expansion tank, rather than air. Search Glen Wilson and his SEAC rebuild. He's used a modified Griffith header chamber which gets rid of the two plastic tanks.
KKson said:
Ah, I understand the question now. Main sealed expansion tank is Ford Capri. The overflow bottle is a TR7 screenwash tank. This is not pressurised. The idea is that this has a few inches of water in it. If the expansion tank relieves then it goes into the overflow tank. When it cools down the submerged pipe allows coolant to be drawn back into the expansion tank, rather than air.
Yes, that's the theory. I found that it worked quite well but the TR7 bottle needed to be removed and emptied into the Capri one from time to time.TA14 said:
KKson said:
Ah, I understand the question now. Main sealed expansion tank is Ford Capri. The overflow bottle is a TR7 screenwash tank. This is not pressurised. The idea is that this has a few inches of water in it. If the expansion tank relieves then it goes into the overflow tank. When it cools down the submerged pipe allows coolant to be drawn back into the expansion tank, rather than air.
Yes, that's the theory. I found that it worked quite well but the TR7 bottle needed to be removed and emptied into the Capri one from time to time.TA14 said:
Yes, that's the theory. I found that it worked quite well but the TR7 bottle needed to be removed and emptied into the Capri one from time to time.
Yes to be honest, I've had to do that too, it's very hard to get a completely airtight seal on a push fit washer bottle cap - a screw cap would work better.As Twinkam says the overflow bottle is open to atmosphere with a few inches of water in it. The outlet tube from the expansion tank is submerged at the bottom so if there is any vacuum in the expansion tank, it draws water back. I have never had to empty the overflow tank on any of my Wedges so do check that the outlet hose from the expansion tank to overflow bottle is sealed. I put a small jubilee clip on it where it exits the expansion tank to ensure a seal on the pipe.
KKson said:
As Twinkam says the overflow bottle is open to atmosphere with a few inches of water in it. The outlet tube from the expansion tank is submerged at the bottom so if there is any vacuum in the expansion tank, it draws water back. I have never had to empty the overflow tank on any of my Wedges so do check that the outlet hose from the expansion tank to overflow bottle is sealed. I put a small jubilee clip on it where it exits the expansion tank to ensure a seal on the pipe.
Even in theory it doesn't work properly. Car gets hot, expansion tank blows out air then water into the overflow which already has some water in it. Car then cools and sucks back the lost volume and fills it with all water: too much water now in the expansion tank 
It never works that efficiently anyway.
My capri one developed a pin hole which sprayed me in the face when I stopped due to broken throttle cable.. Tried fixing it to no avail so went with the Mercedes Benz replacement which I got from ebay. The problem was I had to make the brackets where one was easy, the other not so and I had to make it hang onto the level switch. It works fine but I also had to buy some reducing connectors to get the output pipe down to the right size.
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