A friend has a 1994 Chevy S10 with the 4.3 V6 TBI. The thermostat was staying around 160 and he had no heat, so I changed the thermostat. He has heat now, but the gauge needle will go up to 195, the stat opens, and the needle dives to 160. What would cause this behavior? For the temp to change that quickly, I can only think of an air pocket. Any ideas would be appreciated.
temperature issues??
- Thread starter DoubleDee
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That would be my first reaction too. A bouncing needle usually points to an air pocket.
The only other time I've seen this is where a fellow jeeper used a super Ford electric fan that drew some incredible current and moved incredible CFM and cooled the rad so much that by the time the thermostat got the message, the engine temp was down 30F.
The only other time I've seen this is where a fellow jeeper used a super Ford electric fan that drew some incredible current and moved incredible CFM and cooled the rad so much that by the time the thermostat got the message, the engine temp was down 30F.
Does it eventually stabilize? Sometimes the gauge sender is a long distance from the thermostat so it really sees the big gulp of cool AF incoming from the rad.
Also the cheezy thermostats are sticky while the nicer ones (stant superstat) have smoother action.
Some thermostats also need a tiny hole drilled in the highest part of the flange to let a little coolant bypass all the time. This burps bubbles and makes sure there's flow over the tstat pellet at all times to better signal it.
Also the cheezy thermostats are sticky while the nicer ones (stant superstat) have smoother action.
Some thermostats also need a tiny hole drilled in the highest part of the flange to let a little coolant bypass all the time. This burps bubbles and makes sure there's flow over the tstat pellet at all times to better signal it.
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I've rarely seen a drastic variance in coolant temp. Variable, surely, but not quickly reacting. I do see minor fluctuations with my wife's jeep after I installed a 2 core (or was it 3
) rad. There the sender is at the thermostat housing. Much, I imagine, depends on the volume of the bypass flow.
I think Robertshaw thermostats are the only ones that are truly proportional. Others, like the Superstat try and compensate with a V port (iirc).
Yes, they don't always include a weep hole in the stat. I had to drill one in the cheap one I bought not long ago trying to figure what temp I wanted for the inlet stat.
I think Robertshaw thermostats are the only ones that are truly proportional. Others, like the Superstat try and compensate with a V port (iirc).
Yes, they don't always include a weep hole in the stat. I had to drill one in the cheap one I bought not long ago trying to figure what temp I wanted for the inlet stat.
That is odd my 4.3 in my sierra never fluctuates like that. Burp the system drive it with the resovoir cap on 1 notch not tight. Keep an eye on coolant level as you may need to top it off a bit.
Did he do a coolant flush lately? or any type of repair with the cooling system.
Well the OEM being sticky is because it was made in israel (at least mine was) the stant was US
Did he do a coolant flush lately? or any type of repair with the cooling system.
Well the OEM being sticky is because it was made in israel (at least mine was) the stant was US
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was it oem? some GM thermostats are different than the same temp generic tstats, like they open more slowly or are for reverse flow cooling like my car
Air pockets will do this.
Normally they fix themselves, but you have to give it a few days of normal driving with cold/hot cycles.
Keep the reservoir 1/2 full and check it often for a while.
BTW, it was a good idea to replace the 160 with a 195 for a bunch of reasons.
Normally they fix themselves, but you have to give it a few days of normal driving with cold/hot cycles.
Keep the reservoir 1/2 full and check it often for a while.
BTW, it was a good idea to replace the 160 with a 195 for a bunch of reasons.
Thanks for the ideas. He called me today saying that he hears water moving around under the dash. He is thinking about putting in a new radiator(coolant is rusty looking) so I will drain and refill then. I had never seen a a needle move 30 degrees like that.
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