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JCB with coolant question.

68Chevelle327 · 2023-11-21 23:34

I have a mid 80s JCB 1550B 4x4 and i noticed a slight coolant drip while running. I noticed its leaking under the rad cap, so i went out and bought a new T7 cap and it still leaks. I decided to run it with the cap off and you can see alot of coolant "splashing" inside the radiator (youtube link below).. I don't recall ever seeing this before in old cars I've owned... Any ideas? Thanks

Replies11
  1. #1cosmaar12023-11-22 17:34

    I would say it’s splashing because the machine is vibrating the daylights out of the fluid. I can’t speak on the leak for sure… maybe something is bent? Maybe the cap isn’t sealed entirely right? Are you sure it’s seated?

  2. #2Kevin Foust2023-11-23 12:11

    How is the blow by?

  3. #368Chevelle3272023-11-23 20:38

    Blow by?

  4. #4Kevin Foust2023-11-23 21:16

    Is there any air pressure coming out of the dipstick or oil fill when the cap is off while running?

  5. #568Chevelle3272023-11-23 23:46

    I didn't look. You think blow by is causing this? I know it doesn't smoke while running or use any oil. Just smokes when its cold out while cranking over.

  6. #6Kevin Foust2023-11-24 08:00

    If there are air bubbles/more pressure in the coolant it could be a leaking head. I've seen it before. They sometimes leak to both oil and coolant is why I asked. May just be vibration but if it's pushing past the cap and ir's good, it could be that. Look for oil vapor coming out dipstick tube or oil fill. They start slow sometimes.

  7. #7Vetech632023-11-24 09:22

    They can also do that when the thermostat has been removed and is not regulating the water flow.

  8. #856wrench2023-11-24 10:08

    Are you sure you bought the right rad cap? It appears to have a fairly deep filler seal surface on the neck and you need a two way cap that works for a recovery system if it has a recovery reservoir

  9. #968Chevelle3272023-11-24 22:03

    I really don't know. The old one was your standard T7, so i west out and bout another Motorrad T7 since i thoughtit was the seal leaking. I'll say this it's not stiff to put on like some of the old cars i drove 15 - 20 years ago.

  10. #1068Chevelle3272023-11-24 22:06

    Its hard to tell.i know what your saying. Ive seen in on some cars and i dont see bubbles like that on this. Just alot of splashing as you can see.. maybe this is normal since the coolant fill location is on the motor itawlf? And it shakes the living crap out of it? I do question the cap. If i have they correct one.

  11. #1156wrench2023-11-25 11:24

    By your video, I didn’t see any air bubbles-just vibration.