so here are the symptoms of my problem this week.

1. temp gauge is going up pretty rapidly and hovering close to the red.

2. when i turn on the heater it drops quite quickly into the safe zone

3. the fan is spinning

4. there is a slight leak at the water pump until it gets hot and the water evaporates off.

5. check engine light with 1-2-1 AMM no signal light came on for the first time (hole in air box has been blocked off)


AMM passed all tests except one and this was a sticking point between my wife and I

in the AMM tests listed in the bentley they have one for testing the air mass wire in it they say to remove the connector and test resistance at 2 and 3. surely they mean test on the terminals in the meter and not on the connector. The terminals in the meter were in the correct range for ohms the terminals on the connector were out of range. Another air mass meter test has us checking resistance between terminals 6 and 7 on the ecu looking for around 4 ohms and i got 13 ohms. so i don't know.

cleared the codes and the light has not come back on, no holes in lines including flame trap hose and trap is clean, filter is clean, connections are good.

these are probably unrelated issues. but theres always a chance they connect somewhere

any advice would be great

I'm thinking it's not the AMM for your overheating issue.

Perhaps a poor flowing plugged up radiator. Is it the 25 year old original radiator? Are you maintaining coolant level even with the water pump leak?

Not saying it couldn't happen, but in 35 years of wrenching on my family's cars, I've never had to replace a thermostat that failed in the "closed" position. Done plenty that failed in the open position. I agree that is an inexpensive repair, but it seems to me that many internet car forums throw "bad thermostat" around as a fix for overheating issues without a more complete diagnosis.

And yes, diagnosing a poorly flowing radiator is difficult if not impossible to do on your own with a garden hose.

+1

I too think it could be a clogged radiator that isn't flowing properly. My old 90 acted that way before I sold it. A big clue that it is a clogged radiator is that when you turn on the heater the engine temp goes down. My old car did that too and I had already replaced the temp. compensation board. Is the radiator original? If so, it is overdue for replacement. If not, you could try removing then cleaning and flushing the radiator.

The above only applies if it isn't the temp. compensation board. Try that first as it is an easier and cheaper fix!

--
Current - 95 855 GLT Sportwagon 255k, Formerly - 90 244 DL 300k

Hello,

The AMM cannot really be test on the car with any great reliability. It is an expensive exchange, look and see proposition.
Since you have the heat pipe door blanked off it is even less likely to be your problem.

It should have nothing to do with the temperature gauge in the instrument panel.

Two things that might cause that type of reading. A bad wire out to the sender but that can mean it can go cold and you do not mention that symptom.
The other readings, without the signs the engine is running hot, is a temperature compensation board in the instrument cluster.

They are notorious for going "bonkers" at any given time!
It creates wide swings by using large steps to show changes no matter if it's right or wrong. It is designed to remove slight changes of which no one likes to get scared by!

Do you know if it has been removed?
The pins that it connects into it get a jumper put on the cluster side and the board is tossed!

If you remove it, it will show slight variations of temperature relating to the thermostats operation and tolerance range. This is a good thing, really!

Information on its removal are noted and explained with pictures on Art Benstein web site, Cleanflametrap.com.

Check it out. Art does a great job showing his talents on that site. A wealth of information on the bricks are there.

The water pump leakage could mean it's bad or the seal that fits between the pump and the engines head could be seeping.

Can you tell if the leak originated from a weep hole in the pumps casting under the pulley or from up higher? Antifreeze streaks should be prevalent from the source.
If the board is gone replace the thermostat with a "Wahler" brand thermostat! They stay repetitive and accurate over a longer period of time. Worth the extra buck or two by far!

Phil

Thanks Phil, I'll check out Art's site for the temp sensor board