Cooling System Thermostats - Again!

[James W]

I still have this most annoying thermostat problem of slow warm ups. I replaced the thermostat twice, and in last weeks snow had a cold engine and cold heater in a 40min drive.

Within the first 5 minutes of running the radiator water is warm, so the thermostat is passing water when it shouldn't.

Somebody when I last brought this up suggested that only a genuine Isuzu part works, however I just got one priced at $70 at Blackwells (Christchurch Isuzu agent). But I will be spewing if it too doesn't work.

So any thoughts? Cheaper genunine parts?

[geeves]

I just used a tridon therostat with no troubles There is a bypass to circulate water in the engine maybe this is blocked

[James W]

If the engine bypass was blocked then it would tend to overheat, plus the radiator would remain cold.

[geeves]

Bypass realy only works when the thermostat is closed It allows water to circulate within the engine regaurdless of the therostat. If this didnt happen the water in the termostat houseing might not heat up as quickly as the engine which could cause probs. Once the thermostat is open some water would still follow this path but most would go to the radiator.
I would be checking the thermost very carfully as it might be a dud Place it in cold water and heat checking the temp with a suitable theromiter. Also check that the thermostat is actualy seating properly in the housing Water might be getting past it due to corrosion etc. Maybe a bead of silicon would help but make sure it dosnt get on the mechanism.
If all else fails you could resort to the old fashioned metod of a radiator blind

[maletimaru]

Try the oldest trick in the book

Make up a template / blocking plate and pop it in there and drill a 5/8" hole into it - this works and you will notice a difference

[maletimaru]

Also - I have my thermostat from my 4JB1-T engine and I KNOW it works fine - i can sell it to you if you like - very very cheap at $10 plus postage

I am in Timaru (South Canterbury, NZ)