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Thread: RV8 Overheating

  1. #51
    Join Date
    Aug 2016
    Location
    Waterlooville
    Age
    44
    Posts
    94
    Only issue is I don't own an air compressor!
    Blog: http://pilgrimcobra.wordpress.com


  2. #52
    Join Date
    Oct 2014
    Location
    Bucks
    Posts
    13
    Hi

    Do you have an oil extractor pump for pulling oil out of the dipstick tube for oil changes?

    If you do you could make a coolant filling system like this guy.

    http://forums.mg-rover.org/mg-zt-rov.../315806?page=1

  3. #53
    Join Date
    Oct 2014
    Location
    Bucks
    Posts
    13
    Cheap oil extractor pump on Amazon
    £17

    https://www.amazon.co.uk/dp/B003G2YV..._57ygBbFHG4YR5

  4. #54
    Join Date
    Jul 2012
    Location
    NW England
    Posts
    285
    Don't want to sound like a smart Alec and maybe I'm just the luckiest guy in the world (I think I probably am anyway) but I've had coolant in and out of my (2 off) RV8s several times and never had a problem without any special filling technique, and I can't help thinking that adding simplicity is better than adding complexity in the quest for a solution.

    I changed the inlet manifold and heater feed/return on mine this winter and took the opportunity to have a good look at and think about the cooling circuit and I think the RV8 is quite a simple setup with at least 1 advantage over some others I've seen.

    Looking at the flow and starting at the water pump, coolant is drawn into the pump from either the heater return (cold) and/or the bottom of radiator (hot) and is fed into both sides of the block, it then goes to the rear of each bank around the cylinder walls, at the rear of the block it exits into each head and progreses forward to the fronts where it exits into a chamber in the front of the inlet manifold which houses the thermostat and a feed to the heater.
    when the engine is cold (thermo closed), coolant will progress through the heater and out to the water pump feed, when hot it goes out through the t'stat, through a header tank (on mine) and into the radiator. Rinse and repeat.
    The reason I say this system has an advantage over some is that there is only one route through each bank, not multiple interfaces between block and head, which to my mind gives less opportunity for an air lock.

    Where could an air lock occur? I guess if the engine points uphill air could be left in the front of the block while if it points down hill it could get left in the rear of the heads but even so once the car moves around pitching up and down this should quickly work its way out once the 'stat is open.

    My system is as simple as I've described there, the only plumbing linking the engine to the ouside world is the flow/return to the heater matrix and the flow/return to the radiator, the return is intersected by the header tank, a simple horizontal cylinder with pipes either side for coolant flow and radiator cap on top. This allows coolant to expand and air to escape.

    It sounds like your overheating occurs (if it is overheating) when the engine is already hot and the car slow of stationary which would indicate either lack of cooling in the radiator curcuit (blocked rad' or ineffective fan) or lack of flow into the radiator curcuit. Does anything resist the flow of coolant into, through or out of this curcuit (between the t'stat housing (from the t'stat housing outlet to the water pump inlet)?
    Bear in mind when hot the coolant has two possibilities for flow, it can go through the radiator and through the heater, it will do both but should flow (much) more through the radiator due to the wider hoses and greater resistance of the heater matrix over the radiator. If for some reason the radiator curcuit is more resistive the heater curcuit could act as a "short curcuit" and obviously has less ability to liberate heat. Presumably you don't have a valve in the heater curcuit? That would be a no-no but would enable you to test by cutting it out and forcing flow to go via the rad.
    You could try clamping up one of the heater hoses (once the engine is hot!) and see if temperature drops. DO NOT do this until the 'stat is open

    Apo.ogres for the wordy reply but to summarise
    1) you either have a problem with flow (restrictions in plumbing, pump issues), or
    2) heat liberation such as blocked radiator or airflow through it

    I'd suggest getting one of those I pyrometers, you can get cheap ones and, while they may not be perfect, will at less show the difference between cold, warm, hot & very hot which is probably good enough.

    BTW
    I've heard of people modifying inlet manifolds by joining up the blanked off ports at the rear of the heads, you don't have anything like this on your do you?

  5. #55
    Join Date
    Feb 2007
    Location
    West Sussex
    Posts
    8,002
    one of the issues imho is the long hose runs to and from the header tank on the sumo standard design.
    Crendon Chassis No.49
    Huddart FE428 + toploader

    Not listed in the Shelby Register.

  6. #56
    Join Date
    Jul 2012
    Location
    NW England
    Posts
    285
    Just been out yo the car and had another look at the pipe work, I realise there is an additional route through from the chamber in the manifold to the water pump feed, so even if the heater was blocked there would still be a circuit for coolant to flow, although obviously with no cooling at all.

    Quote Originally Posted by KevinW View Post
    one of the issues imho is the long hose runs to and from the header tank on the sumo standard design.
    Unfortunately Kevin I don't know the specifics of the Sumo design but my radiator sits quite far forwards and from the header tank there is quite a long run forward and across the car to the top of the rad, can't see why it would be longer on the Sumo but as said I'm not familiar with the design. I suspect there may also be some more "creative" plumbing involved.

  7. #57
    Join Date
    Aug 2016
    Location
    Waterlooville
    Age
    44
    Posts
    94
    Thanks for advice and break down GDCobra, honestly because this is my first car and I've been learning a lot as I go, any help is valuable.

    Thankfully I had Tony around on Saturday who had a look at the car with me. I'd changed the fan switch to an 82deg one, checked the stat which was fine, checked the plugs all ok, and we filled the remains of the system up again with some wetter water and normal water. If I'm honest it has been getting better and I was probably panicking a little, but I just want this go well.
    Anyway after doing this and Tony noticed I had the standard Pilgrim grill on the front, which came off, the car sits nicely around 90, will put a replacement on for the IVA. We had running for a while, certainly a lot longer than I had previously, so hopefully we got all the air locks out and I've altered a few things to help the whole system.

    I have my pre-MOT tomorrow so fingers crossed that will go ok and I'll see if it picks up any other issues.

    Thanks everyone for the suggestion, I'm hoping I've finally cracked it now!
    Blog: http://pilgrimcobra.wordpress.com


  8. #58
    Join Date
    Jul 2012
    Location
    NW England
    Posts
    285
    Quote Originally Posted by Sportstog View Post
    Thanks for advice and break down GDCobra, honestly because this is my first car and I've been learning a lot as I go, any help is valuable.

    Thankfully I had Tony around on Saturday who had a look at the car with me. I'd changed the fan switch to an 82deg one, checked the stat which was fine, checked the plugs all ok, and we filled the remains of the system up again with some wetter water and normal water. If I'm honest it has been getting better and I was probably panicking a little, but I just want this go well.
    Anyway after doing this and Tony noticed I had the standard Pilgrim grill on the front, which came off, the car sits nicely around 90, will put a replacement on for the IVA. We had running for a while, certainly a lot longer than I had previously, so hopefully we got all the air locks out and I've altered a few things to help the whole system.

    I have my pre-MOT tomorrow so fingers crossed that will go ok and I'll see if it picks up any other issues.

    Thanks everyone for the suggestion, I'm hoping I've finally cracked it now!
    Well hope that's sorted it, good luck with that issue and the IVA

  9. #59
    Join Date
    Aug 2016
    Location
    Waterlooville
    Age
    44
    Posts
    94
    Thanks all

    Had a pre MOT today, all looks good to pass to normal MOT, emissions were sorted for the age of the engine and are quite a bit lower. Brakes were all good and a decent pass and the head lights have been set up correctly, as they were a little low. I've got a few hoses that need adjusting so they are rubbing on other areas but otherwise all is good. Also had the car running for quite a while and no overheating (phew) looks like I'm good to go for the IVA in two weeks once I adjust the last few bits
    Blog: http://pilgrimcobra.wordpress.com


  10. #60
    Join Date
    Dec 2008
    Location
    Exeter
    Posts
    119
    Although rather late in commenting I can confirm that the Sumo radiator set up, 3.5 RV8, with the Pilgrim mesh grill will tend to overheat in hot weather rather easily. Removing the grill made a huge difference and no problem except in the usual traffic jams triggering the fans! Temperatures of 25 degree C and above definitely causes problems with the Pilgrim mesh. I put the mesh back in place in mine but with the intention of replacing it with a stainless steel square mesh one day, I still haven't reached that day yet! In my case the engine has now done ~16K miles and is probably well run in but your new build engine may well run a lot hotter before it loosens up needing all the radiator air flow it can get. Good luck with the IVA.

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