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Thread: Foaming expansion tank at revs/ coolant overflow/ what tank do I have?

  1. #1
    Join Date
    Nov 2019
    Location
    Hudson valley, ny
    Posts
    22

    Default Foaming expansion tank at revs/ coolant overflow/ what tank do I have?

    I've had an issue lately where with higher revs and longer WOT pulls, the expansion tank seems to foam/aerate to the point where it starts to push coolant past the cap. Once I use more sensible throttle the level settles back out. It seems to be aerating via the top bypass hose. I've tried repeated bleeds and burps. Rad did some have a small leak I had professionally repaired. I've taken some coolant out of the level to try and prevent this, picture show is level at full cold. I may just replace the header tank and cap just to be safe. Any ideas?

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    Birkin S3, Dunnell Zetec Powered
    Toyota Celica GT-S, Toyota MR2 Turbo GT-S, Lotus Elise (RIP)
    Yamaha Bolt C-Spec, KTM 625 SMC, Yamaha TW200 scrambler, Yamaha SR250 tracker, Honda CB360 bobber

  2. #2
    Join Date
    Jun 2013
    Location
    N. California
    Posts
    126

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    I was having some weird cooling level issues that turned out to be the cap. The cap on your Birkin appears to be the same as the one on my Caterham. The two p/n's I found for a replacement were PCD100160 and GRC184. The cap I ended up with was an OEM Rover cap. I'd suggest you try that 1st as it's inexpensive and easy.

  3. #3
    Join Date
    Jul 2013
    Posts
    498

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    Too long in isolation??? That tank looks like good legs and a cute butt to me.

    Too full would have been my suggestion, but the photos do not look like it. However, if the temp gauge is not reading hot, maybe you shoule lower cold level at tank even more and think of it as an expansion tank. Changing cap, as suggested, is always a cheap try.

    What does it do if you loosen cap (pressure)? How hot is it really running?

  4. #4
    Join Date
    Oct 2006
    Location
    South Lyon Michigan
    Posts
    219

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    You my be seeing cavitation at higher rev's. If the engine is not over heating, slow down the water pump speed.
    Dave W

  5. #5
    Join Date
    May 2018
    Location
    Albany, NY
    Posts
    378

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    Quote Originally Posted by Dave W View Post
    You my be seeing cavitation at higher rev's. If the engine is not over heating, slow down the water pump speed.
    Dave W
    I'm having cooling woes myself and starting to think that cavitation is my problem. Original 19 year old Zetec water pump and it has plastic fins. Only thing I didn't change (and timing) during last tear down.

    My coolant seems to never get rid of bubbles coming out and also dramatically expands once it gets hot and over flows out of cap.

    I do suggest getting one of these , just don't buy the generic Amazon one or you'll have to make your own adapters like I did.

    I had to butcher a spare cap and Dremel existing adapters to make it work. Not recommended

    Last edited by Vovchandr; 07-22-2020 at 07:46 AM.
    2001 Caterham Superlight R

  6. #6
    Join Date
    Nov 2019
    Location
    Hudson valley, ny
    Posts
    22

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    Quote Originally Posted by Vovchandr View Post
    I'm having cooling woes myself and starting to think that cavitation is my problem. Original 19 year old Zetec water pump and it has plastic fins. Only thing I didn't change (and timing) during last tear down.

    My coolant seems to never get rid of bubbles coming out and also dramatically expands once it gets hot and over flows out of cap.

    I do suggest getting one of these , just don't buy the generic Amazon one or you'll have to make your own adapters like I did.

    I had to butcher a spare cap and Dremel existing adapters to make it work. Not recommended

    that appears to be the same tank I have, any idea where it's sourced from?
    Birkin S3, Dunnell Zetec Powered
    Toyota Celica GT-S, Toyota MR2 Turbo GT-S, Lotus Elise (RIP)
    Yamaha Bolt C-Spec, KTM 625 SMC, Yamaha TW200 scrambler, Yamaha SR250 tracker, Honda CB360 bobber

  7. #7
    Join Date
    Sep 2006
    Location
    Southeastern Pa.
    Posts
    2,864

    Default

    It’s from a rover. Caterham used to stock them
    Mangia bene, Ridi spesso, Ama molto, Guidare veloce

    2000 Caterham Superlight #123
    1.8L VHPD Rover K Series
    2009 Caterham SV
    2.3L Cosworth Duratec

  8. #8
    Join Date
    Dec 2013
    Location
    Owings Mills, MD
    Posts
    143

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    Have had the exact same problem in the past with my Zetec powered SLR. High revs lead to bubbles into the overflow tank (same tank as depicted) and then overflow out with loss of coolant and overheating. Initially thought must be air in system. Bled everything-no air and same problem. Then began to note black slightly oily residue building up in the overflow tank. Given overheating and now what appeared to be exhaust fumes in the overflow, figured blown head gasket. Took the car to George Alderman who replaced head gasket and made some other 'while were in there' changes. Seemed to run fine for a while afterwards. Then back on track and same thing as described with high revs. Back to Aldermans. Both George and Paul seemed stumped as to whats up. They decide to look at how the cooling system was arranged on the Ford Contour/Focus and rearranged what was initially the stock plumbing on my car for a Rube Goldberg rearrangement of the plumbing. Also jumped the temp sensor which controls the radiator fan so it now runs constantly. When I picked it up- wasn't thrilled at what had been done but too late at that point. Car seems to run fine. No overheating or spitting out through the overflow tank however- I haven't tracked the car since the plumbing was changed. Bottom line- before I did ANY of that- I'd get a new overflow cap AND only run the car with enough antifreeze to just begin to show in the bottom of the overflow tank, not halfway up. It will still bubble into the overflow but wont leak or likely overheat.

    I know you'll want to see how the plumbing was rearranged. Will try to get some pictures.

    TurboTom lurking on here? Any thoughts?

    Jim

  9. #9
    Join Date
    May 2018
    Location
    Albany, NY
    Posts
    378

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    Quote Originally Posted by FE07 View Post
    Have had the exact same problem in the past with my Zetec powered SLR. High revs lead to bubbles into..
    Jim
    Pretty much same problems as me to a T right now on my Zetec.

    I thought had gasket for sure, gas escaping into coolant.

    However did leak down test. Good. Then did the exhaust fumes in coolant test. Also good.

    Engine is healthy.

    A friend of mine is suggesting fitting a swirl pot as a solution instead of overflow. I'm hesitant but likely will try it.

    I might try running less fluid and getting another cap ordered up.

    The drastic expansion of the fluid while at temp and revving is puzzling
    2001 Caterham Superlight R

  10. #10
    Join Date
    Dec 2014
    Location
    Los Angeles
    Posts
    297

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    Stock water pumps will almost assuredly cavitate at high rpm. All fixed pitch propellers are optimally effective in a fairly narrow rpm range. To deal with this, you can either run an electric coolant pump (Davies Craig or others) or plumb in a swirl pot to de-aerate the coolant before it continues through the system. The guys who run Evans NPG coolant are advised to reverse the coolant flow for best performance but this strategy really only works for NPG coolant due to itís fluid properties. I have run the Evans stuff in a 944 at Willow Springs in the summer with no problem but most sanctioning bodies wonít allow it any longer. If you spill some on the track, it is REALLY greasy. I believe the Evans website has a couple of excellent technical articles on coolant plumbing.

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