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  1. #1
    Join Date
    Dec 2016
    Location
    Royal Tunbridge Wells
    Age
    28
    Posts
    40

    Engine cutting out in traffic?? (Overheating?)

    Hi there,

    Just went to take the cobra out to meet a friend for lunch about 15 miles away or so. Was fine on the A-roads going along very quickly, and also fine poodling around through the lanes/through towns.

    However, I ran into quite a bit of traffic for about 5 minutes or so and the engine just turned off. I turned it back on and it reluctantly started, but then about 30 seconds later it just cut out.

    Had to get some builders in the van behind me to push it off the road. Let the radiator fan run for 5 minutes or so, then started up no problems.

    10 minutes down the road later, I pull into a side road to do a U Turn and it just cuts out again. Again - wont start. Leave it 5 mins with radiator on and it starts up again.

    Then I drove about 20 minutes home and it was fine the whole way. Just seems to be when in traffic or low idle?


    The car currently idles around 1250rpm

    It has one big fan at the front, thats probably like (if I had to guess) 21-22" Diameter.

    Another thing worth mentioning, is that the little samco silicon hose that is the excess water tank escape hose, was spitting out quite a bit of water - which directly lands on the exhaust (because its not long enough) and thus causes quite a bit of steam to come up through the bonnet. But this only happens when stationary and the engine is off. I'm not sure if this is related - or its doing it the whole time, but when im driving - the windspeed cools it / doesnt let it drip directly onto the exhausts?

    Does this sound like an overheating problem to you guys?
    Do you think its related to the water tank issue?
    __________________________________________
    'Green' Dax Cobra with Ford 351 Windsor / Tremec TKO 600

  2. #2
    Join Date
    May 2011
    Location
    Flimwell
    Posts
    866
    Yes, definitely sounds like an overheating problem to me.
    I’ve been struggling with a similar problem which turned out to be an airlock.
    Where abouts in the system is the fan thermostat/switch?
    Colin
    Dax Standard Chassis. Ford 302, AOD auto, DB s/s sidepipes, 2017 T reg.

  3. #3
    Join Date
    Sep 2007
    Location
    Hilperton,Wiltshire
    Posts
    2,607
    That seems a very fast idle.


    Andy

  4. #4
    Join Date
    Dec 2016
    Location
    Royal Tunbridge Wells
    Age
    28
    Posts
    40
    Quote Originally Posted by 1dayiwill View Post
    Yes, definitely sounds like an overheating problem to me.
    I’ve been struggling with a similar problem which turned out to be an airlock.
    Where abouts in the system is the fan thermostat/switch?
    How did you figure out it was an airlock? How do you solve that?

    I dont (think) I have a fan switch. There must be a thermostat somewhere, as it comes on by itself.

    Would the thermostat be near the fan?

    Quote Originally Posted by corn plaster View Post
    That seems a very fast idle.


    Andy
    Yeah, when I bought it (back in November) it was idling around 750-800, but I found when I pulled up to stop (Junction, traffic lights, give way signs etc) it would just cut out immediately.

    Its like it would go to 750-800, then drop a little below and just cut out. So I increased it to 1200-1250 and the problem has gone away since.
    __________________________________________
    'Green' Dax Cobra with Ford 351 Windsor / Tremec TKO 600

  5. #5
    Join Date
    Sep 2009
    Location
    Leeds
    Posts
    2,954
    Is it hesitant to accelerate when it does this blackmamba (name?) ?? if so, it sounds like it could be fuel vaporisation - mine has been doing the same - went for MOT on Tuesday and it was fine driving there, but had a similar problem to you when starting car after MOT - i need to try and reduce temps around the carb area, even though running with a 1/2" phenolic space. Problem only seeming to happen when idling in traffic and not moving forward.

    Will look about wrapping exhausts again (they were previously, but all the exhaust wrap was disintegrting and torn, so i'd removed a lot of it prior to it going in for engine rebuild)

    Agreed with Andy (corn plaster) 1250 seem very high for idle, mines around 750-800 (+- 50)

    rgds
    Gary
    Conny - A Carnival Red Metallic (paint code Ref: Jag CGG/1811) Southern Roadcraft V8 ( SRV8 ) with 383ci stroker chevy.

  6. #6
    Join Date
    May 2011
    Location
    Flimwell
    Posts
    866
    [QUOTE=blackmamba;578373]How did you figure out it was an airlock? How do you solve that?

    I dont (think) I have a fan switch. There must be a thermostat somewhere, as it comes on by itself.

    Would the thermostat be near the fan?

    The radiator shouldn’t spew out a load of coolant unless it’s well above boiling temperature.
    You do have a thermostatic switch in your system somewhere, that’s what turns the fan on. It is usually somewhere near the top hose but could be anywhere on a kit car.
    To solve my problem I bought one of these :- https://rover.ebay.com/rover/0/0/0?m...2F222324674166
    But actually solved the problem by bypassing my heater.
    However, I don’t think the cutting out is necessarily down to the overheating.

  7. #7
    Join Date
    Dec 2016
    Location
    Royal Tunbridge Wells
    Age
    28
    Posts
    40
    Quote Originally Posted by nealgs View Post
    Is it hesitant to accelerate when it does this blackmamba (name?) ?? if so, it sounds like it could be fuel vaporisation - mine has been doing the same - went for MOT on Tuesday and it was fine driving there, but had a similar problem to you when starting car after MOT - i need to try and reduce temps around the carb area, even though running with a 1/2" phenolic space. Problem only seeming to happen when idling in traffic and not moving forward.

    Will look about wrapping exhausts again (they were previously, but all the exhaust wrap was disintegrting and torn, so i'd removed a lot of it prior to it going in for engine rebuild)

    Agreed with Andy (corn plaster) 1250 seem very high for idle, mines around 750-800 (+- 50)

    rgds
    Gary
    (Alex is my name )

    Once it starts up again, it accelerates as usual.

    [QUOTE=1dayiwill;578376]
    Quote Originally Posted by blackmamba View Post
    How did you figure out it was an airlock? How do you solve that?

    I dont (think) I have a fan switch. There must be a thermostat somewhere, as it comes on by itself.

    Would the thermostat be near the fan?

    The radiator shouldn’t spew out a load of coolant unless it’s well above boiling temperature.
    You do have a thermostatic switch in your system somewhere, that’s what turns the fan on. It is usually somewhere near the top hose but could be anywhere on a kit car.
    To solve my problem I bought one of these :- https://rover.ebay.com/rover/0/0/0?m...2F222324674166
    But actually solved the problem by bypassing my heater.
    However, I don’t think the cutting out is necessarily down to the overheating.
    Just checked the car and definitely no manual fan override switch in the cockpit.


    Can we simplify this a bit, as im really confused lol.

    I thought the Radiator was the big bit at the very front of the car, that the fan is connected to?
    The is it the Radiator Water Tank (?) that is the opposite side almost near the dash. And the Radiator Water Tank (?) is the one that is spewing out coolant, not the bit by the fan.

    I saw on Car Builder Solutions you can get a waterless coolant liquid to top that up with. Maybe that would be better so it isnt spewing so much out?

    Or maybe I should buy a new samco hose that is longer, so it goes AROUND all the exhausts and doesnt cause steam, but it will drop directly onto the floor?

    https://www.carbuildersolutions.com/...oolant-5-litre



    What do you think could be causing the cut out if its not overheating? Bearing in mind its only happening in traffic / idling - and its running fine when theres no traffic?
    __________________________________________
    'Green' Dax Cobra with Ford 351 Windsor / Tremec TKO 600

  8. #8
    Join Date
    Dec 2016
    Location
    Royal Tunbridge Wells
    Age
    28
    Posts
    40
    Just taken some pics. I havent tried to make the car look pretty or anything for you guys - so it looks a bit grubby !

    I can take a video if that would be better for you guys to understand the layout of things?




    __________________________________________
    'Green' Dax Cobra with Ford 351 Windsor / Tremec TKO 600

  9. #9
    Join Date
    Jan 2005
    Location
    leatherhead,surrey
    Posts
    987
    # What do you think could be causing the cut out if its not overheating? Bearing in mind its only happening in traffic / idling - and its running fine when theres no traffic?#
    ful perculation? - i e fuel so hot it boils in the carb....
    or ignition system cutting out with heat? - prob less likely given it restarts so easily
    neil

    ps probably not the best siting of the expasion bottle right next to the carb....
    good for access / less chance of air trapped/airlocks perhaps etc but a litre or more of hot water next to summat heat sensitive isnt recommended
    Last edited by neil still building it; 29-06-18 at 02:21 PM.

  10. #10
    Join Date
    Jan 2002
    Location
    Woodham, Surrey, UK.
    Posts
    542
    What carburettor do you have? My Edelbrock suffered from fuel vapourisation, and wouldn't start from hot. Have a look here - http://how-to-build-a-pilgrim-sumo.w...fueling-system . Works fine now. Also here - http://how-to-build-a-pilgrim-sumo.w...on-thermostats

    B

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