Not Much Heat.

[900Trophy]

Hi! This is my first post.

I've viewed some of the other "no heat, low heat" threads here.
I've got a '92 Buick Roadmaster with 299,000 miles on it. I'm on my fourth or fifth thermostat. I've tried Stant SuperStat and Murray heavy-duty ones and so on. The best yet have been the SuperStats but not one of them seems to be able to keep heat in the engine. I understand these are big iron blocks and take a while to heat up, but it's just below freezing where I'm at and even with a *new* block heater and the rad blocked off it still takes a long time to heat up. What I'll see on the gauge is this:

temp will slowly rise to the point where it his about 160 (on the gauge), rise somewhat faster till it hits 220, hang there for maybe 30 seconds, and then rocket to maybe 120. From that point forward, it will go back and forth between maybe 170-180 (on the gauge) and 120 until it eventually settles in around 160. I have no reason to trust that the gauge is accurate, but at least it's consistent.

As I said earlier, I've replaced the thermostat 4 or 5 times in the last 3 years. I've used traditional-style thermostats (snap open, snap closed) and the SuperStant (wax-based). I prefer the SuperStants at this point.

I've also had the coolant flushed at the local Valvoline (they did a really nice job, actually) and, for a while, I had heat again. However, I barely get heat now.

I took a digital laser thermo thinger and pointed it at the hoses that go in and out of the heater core. On the engine side of the restrictor I see about 180F. On the other side of the restrictor (still on the input side to the heater core) I see substantially less, forgive me that I don't recall but it's something like 120F.

The upper heater hose gets plenty hot, 170-180 (which means the fluid is probably closer to 190 or more) so the thermostat does appear to work.

The water pump is original. Actually, everything but the alternator is original, other than filters and such. The engine runs reasonably well, but is def. getting tired.

I've talked to others and pretty much they all say one of two things:

1. all Buick Roadmasters are like this
2. your heater core is plugged, either replace it or **carefully** try flushing it.

What do y'all think?

This is not a big deal when the temp is 20F and up, but it gets COLD here sometimes and much less than 20F and I'm not sure I'd even be able to defrost my windows.

[bocoogto]

No, all Roadmasters are not like this. My '93 rises to about 190 degrees and stays there. Heater works VERY well, even at below zero temps. You do need a 192 degree thermostat for the heater to work properly. With a 180 degree stat, heater does not work right.

I had a '77 Pontiac 400 v8 that did exactly what your Roadmaster is doing. Temp rose to above 220 when warming up, then dropped to thermostat level. Problem was an air bubble in the cooling system. That may be what's wrong with your Buick.

[j cAT]

the heater hoses are hot and warm this means the heater core is restricted.. remove the hoses at the engine and flush out with a water hose and then use air pressure if possible...then reverse this ...you will see debris in the coolant waste container...

BOTH HOSES SHOULD BE HOT...THEN YOU WILL HAVE HEAT.

this is done every coolant change and so far all are happy...0 deg f last night..and plenty of heat..