I have a question for other 1991 up GM B body wagon owners about warmup times. Before we begin let me state the following. I recently acquired my 92 and it had a 170 degree thermostat in it. Other than being way too cold, it did work (I tested it by checking it's operation in a pot of hot water). I replaced it with a 205 thermostat to help improve fuel economy and get more heat in the wintertime. I tested it in the pot of water as well and I know it works properly. I installed it and while it certainly has improved the fuel economy and warmup time, it still takes forever to heat up and it cools down a lot more than it should while driving. I suspect that it is because the heater hoses on this car are set up to bypass the thermostat (like I have seen on Chevy trucks) where water is returned to the radiator tank, not the engine. This would allow a substantial amount of cold water to enter the engine via the heater circuit even when the thermostat is closed. On the pre-91 bodystyle, the heater was supplied from the back side of the engine, and the water was returned to the water pump. I am wondering if this phenomena is something that other owners of this bodystyle have observed. I intend do try to figure out some way of converting the engine back to the older water flow setup to facilitate a more rapid warmup and a more stable operating temperature at a warmer temperature. I want to get some input from other owners on this subject. 1992 Chevy Caprice Estate 5.0L TBI
Are you sure you have a temperature issue as opposed to a heater core flow issue? I've heard of a number of instances over on the Longroof forum of folks having to flush/backflush their heater cores due to partial clogging.
Thank you for the responses. First let me say that the coolant level is 100% full. Also, the problem is the actual operating temperature. I have sufficient heat output from the heater, but the engine tends to run too cold despite the hotter thermostat. I know that the factory dash gauge is no paragon of accuracy, so I hooked up my Tech 1 to the ALDL and monitored the coolant temperature. The engine barely ever reaches 210 degrees. When it does it is only briefly there. it is running in the 180-190 degree range most of the time and that is with a 205 degree thermostat. with the old thermostat (which was 170 degrees, not the 195 degrees recommended by GM) it would barely reach the first line on the coolant temperature gauge (about 150 degrees on the Tech 1). Needless to say, it is running much warmer now and my fuel economy has drastically improved, but In feel that I am still leaving some efficiency on the table because of this inability of the engine to maintain a 200-220 degree operating temperature. It runs warmest when idling in gear immediately after running the engine under load (such as stopping at a red light), or at heavy engine load (such as climbing a steep hill) when it reaches about 215 degrees and starts cycling between 205-220 (which is about right for a 205 degree stat). But as soon as I begin driving at light to part throttle (or if I slightly elevate engine rpm in neutral) it cools right down to the 180-190 range, suggesting that the water pump is pushing colder water from the radiator through the engine, even with the thermostat closed.
I wouldn't want my engine running @220. getting to hot. The 180-200 degree range is good. My roadmaster (96) runs @ 190-200 all day long. Never had an issue with heat and in the summer never has boiled over.
We had a car in the shop many years ago with the same problem....it was a pre-computer car. Customer complaint was no heater in cold weather. Could never get it up to operating temperature. Tried everything that you did to no avail. We never did figure it out, but concluded it must have a super-efficient cooling system. We ended up blocking of part of the radiator, like they do on diesel trucks.
Has the fan clutch been tested? What you're describing could result from a clutch that is engaging all the time or at lower than desired temperature.
Unfortunately it also is functioning normally. It might actually even be weak. It is fully engaged on cold start up for about 15-20 seconds, then the roar subsides and it never speeds back up. I blocked the radiator with cardboard and at an indicated 208 degrees on the Tech 1 it started to elevate in speed (engine at 1500 rpm) and was fully engaged by an indicated 223 degrees. The only explanation I have is the way the heater dumps into the radiator tank; it is allowing the engine to draw some cold water with the thermostat closed. I might have to content myself with 180-190 operating temps for now. I am aware that TPI c\Camaros and 'Birds with 305 and 350 V8s used a 205 degree stat from the factory and ran at 220 degrees, so I am not afraid of engine damage in that range. I am looking to maximize my efficiency wherever possible. I have already taken the lead out of my right shoe, which was where I got the biggest gain.
I have already taken the lead out of my right shoe, which was where I got the biggest gain. Yeah, I understand...but where's the fun in that?
Many years ago in a land far away where winters were cold, we always blocked about half the radiator in all our cars to get more heat. You are lucky your car runs cool. Most people complain of overheating. Dress for winter and put away the shorts and tee shirts till April.
LOL! I had Gastric bypass in July and I have lost 124 lbs, so my problem isn't shorts and T shirts, it's NO INSULATION! Seriously though, I have plenty of interior heat, That isn't my convern. I just want to get more engine heat to get the best possible fuel economy. When I got it I was getting 13 MPG due to the cold stat, an exhaust leak, and a bad O2 sensor. Now I am getting about 21 MPG (no highway trips yet). Just trying to get a little more.
argo, have you checked the function of the heater bypass valve? With the temperature set to maximum "Cool" on the A/C controller, the hose going from the valve to the radiator should not have any coolant flow. That hose should be cold to the touch. If warm coolant is being diverted to the radiator instead of being recirculated between the water pump and the heater, that could cause what you're experiencing.
