About two months ago I replaced my intake gasket (due to oil leak from china wall) along with new 195 thermostat, since then on gold days it does not seem to get up to temp. The temp needle reads just under half way. I checked the temp of the outlet hose from the thermostat when warming up the engine, It stays cold until it reaches temp when idling but when going down the road it drops quit a bit. Just before I put it away for the winter it came up to temp going down the highway for a short period then right back down. Could I have a sticking thermostat or other problem. I also replaced the EGR valve and upgraded to Bosch III' from Jon at FIC. I have a 1990 C4 with 163,000 on it.

 

Does the '90 have a digital temp display? If so, what does it say?

 

No its analog, Has 100 at bottom and 260 at top and no marks in between so you have to ques.

 

I'd vote for stuck T-stat....do you know if your stat has a bypass hole in the flange? or the safety design that locks?

Some "safety" stats come with 1 or 2 holes drilled in the edge so there is always some water able to pass...in case the stat pellet fails and cannot open. A Full on "safety-stat" will lock open the first time it breaks 230-240 IIRC and stay fully opened until you take it out and manually release the mechanical latch on the T-stat shaft.
This is another example of how the T-stat only manages the minimum temps...A 180 stat should give you a minimum temp of about 180...and get you there in minutes...not miles.
Sure does suck having to use the defrost when the engine is stone cold...a/c blowing more cold air in there while your fingers go numb waiting for the thing to warm up...Polar (no pun) opposite of the August complaint!

As long as the engine gets up to 150+ it should be going to CL operation and running normally. Mine makes the "shift to closed loop" at exactly 158...everytime. On cold mornings that may take awhile.

The downside (to be concerned about) to extended cold operation is running rich & dirty, and the oil not getting hot enough to boil off moisture that will eventually form sludge. Short hops and low temps cause more wear than cruising all day at freeway speed.

One other thought....is the orifice still in the intake for the heater hose? Thats there to keep some tension on the intake water so the intake stays full...so the water has some resistance and builds a slight pressure and backs up to fill the intake. If the water is allowed to exit too easily it leaves "hot spots" or dry spots in the heads and intake that can cause other problems. Hard on gaskets and temp control too.

 

[QUOTE=leesvet;1582419396]I'd vote for stuck T-stat....do you know if your stat has a bypass hole in the flange? or the safety design that locks?

Some "safety" stats come with 1 or 2 holes drilled in the edge so there is always some water able to pass...in case the stat pellet fails and cannot open. A Full on "safety-stat" will lock open the first time it breaks 230-240 IIRC and stay fully opened until you take it out and manually release the mechanical latch on the T-stat shaft.
This is another example of how the T-stat only manages the minimum temps...A 180 stat should give you a minimum temp of about 180...and get you there in minutes...not miles.
Sure does suck having to use the defrost when the engine is stone cold...a/c blowing more cold air in there while your fingers go numb waiting for the thing to warm up...Polar (no pun) opposite of the August complaint!

As long as the engine gets up to 150+ it should be going to CL operation and running normally. Mine makes the "shift to closed loop" at exactly 158...everytime. On cold mornings that may take awhile.

The downside (to be concerned about) to extended cold operation is running rich & dirty, and the oil not getting hot enough to boil off moisture that will eventually form sludge. Short hops and low temps cause more wear than cruising all day at freeway speed.

One other thought....is the orifice still in the intake for the heater hose? Thats there to keep some tension on the intake water so the intake stays full...so the water has some resistance and builds a slight pressure and backs up to fill the intake. If the water is allowed to exit too easily it leaves "hot spots" or dry spots in the heads and intake that can cause other problems. Hard on gaskets and temp control too.[/QUOTE

The new T-Stat I put in is the kind that stays open, I will swap it out before next spring when I put it back on the road. Thanks.