Fluctuating temp gage

[Jppr26]

So I’ve been driving my 87’ v20 with a 350 motor for about two months now and I’ve noticed that whenever I accelerate, drive slow, or drop a gear to pull even a small hill my temp gage climes to the 210°-220° mark then it drops back down. I have installed a new water pump, t-stat, and coolant tank. My radiator is a bit crusty, and probably the next thing I’ll replace but I’m not loosing any coolant, is this normal?

 

[1987 GMC Jimmy]

What about your fan clutch? The “drive slow and temp gauge goes up a little” part makes me zero in on that. Do you trust your temp gauge? Do you still have the factory radiator? Don’t throw it away if you do; get it fixed. If not, it’d probably still be cheaper to get it rodded out if it’s not leaking, but I’d say do as you wish when it comes to dealing with aftermarket radiators. They’re nothing too special. My factory radiator had the crusty buildup at the ends of the tubes, and it looked brand new after I had it rodded out.

 

[Obwonkonobe]

A new aluminum 4 core radiator brought my small block to 180 at all times, I think pep boys sells one for pretty cheap

 

[Jppr26]

When I said crusty I meant it’s in bad shape, missing patches of fins between the tubes and some mushed in, I’ll replace it befor I have it cleaned out. Fan clutch seems good has resistance

 

[Jppr26]

So I looked at the fan side of my radiator and this is what I found

 

[Jppr26]

Ok how do I add a photo? It’s worse then I thought probably a third of the cooling fins were gone

 

[Jppr26]

You must be registered for see images attach

 

[Jppr26]

What can I say other than coastal trucks can suck, your money that is

 

[Jppr26]

Well got the new radiator in yesterday, and took it for a drive, the truck ran around 155° on the gage and about 185° when I was running it hard. Before it would run at around 185° and if I got on it it would jump to about 220° then calm down after a bit

 

[Snoots]

Glad you got that fixed!

Now what?

 

[Jppr26]

Next...figure out why the new sending unit on the left side ain’t working, I’ve replaced everything I can find to make it work again, it was working fine after I replaced it, then one day just up and shat the bed. I’m gong to pull the bed and check wiring and function

 

[clendon1]

In my 76 w/ 468 I run an aluminum 4 row radiator w/ stock clutch fan (7blade bb ) and temp stays @ 180-190 w/air on in 90 degree heat. You also want to run a shroud.

 

[Jppr26]

Have a shroud, stock 3 blade fan, and clutch