92 s10 temp fluctuating

[NtheFamily]

Okay, I have a '92 s10 that I bought last year with 139,000 miles on the 4.3. I have installed a new radiator, new upper and lower rad. hoses, new water pump, new thermostat and new oil pressure sending unit.

Few questions:
1) When I drive it somewhere, the temperature gauge will climb to about 210 or a little higher then go down to about 195 - 200 during the first several minutes or approximately first 20 miles of driving it (been doing this since I bought it even before I put the new stuff on). I put a 195 thermostat in it. Why does the temperature fluctuate so much? Will this harm the engine since the temperature does go down?

2) I replaced the oil pressure sending unit since the original one was leaking. When it is firsted cranked up and I drive it for 20 miles or so, all is fine (50 - 60 lbs on oil pressure gauge), but when I stop at a red light it drops to about 16 lbs. Is this normal lbs. of oil pressure at a stop? If not, what is normal?

3) Can you by new 4.3 motors for it from Chevrolet that is an easy swap and if so, has anyone priced them ?

Other than that the truck runs great, gets great gas mileage (from what I'm used to getting from my '85 4x4...which is 9 mph) and is not banged up.

Thanks for all and any ifomation.

[old Rusty C10]

mine does the same thing with the oil its cause its a higher mileage motor. AS long as i have over 10 PSI oil at idle im happy
the temp sending unit may be bad or the thermostat could be bad. Ive had them bad brand new
you can get a crate GM motor cheaper than other rebuilts and if youre handy its pretty easy to swap get yourself a haynes manual first

[68C15]

bad stat will cause the temp deal. it is waiting too long to start opening and having trouble regulating the temp. this is assuming you have all the air bled out. we use nothing but the superstats from Stant/Gates.

have you verified the oil pressure with a known mechanical gauge? I have a customer with a 92 Astro (same engine) with 247,000 miles and it holds 30 PSI at hot idle/stop light.

IIRC GM sells a Goodwrench engine for your application for ~ $2100

[protrash64]

I dont think you have a temp issue at all. Takes a bit for the stat to open and then the cool water flows thru the engine and cools it off. It then stabilizes. Thats how all my trucks do it, too.

[NtheFamily]

Thanks guys for all the info. Kind of makes me feel a little better.

{have you verified the oil pressure with a known mechanical gauge? I have a customer with a 92 Astro (same engine) with 247,000 miles and it holds 30 PSI at hot idle/stop light.} no i have not verified it with a mech. gauge 68C15, i guess i might need to check on that.

{this is assuming you have all the air bled out} ....What is the proper way of bleeding the air out of the system? I believe i need to try this.

Thanks again to all.

[old Rusty C10]

if you go tot he 73/87 section there is a post by Ruralroute c30 there which deals with bleeding his system which is pretty well like yours...

[NtheFamily]

Thanks ol rusty C10.