73 164 Runs Cold

There is one issue I am trying to address. I recently had some work performed. Before it would not run, it would start but not run. Now the engine runs much cooler than when I had it. When I first received the car, it would run a bit on the engine temperature ran
a bit on the high side. The mechanic said the coolant sensor showed 165 F but the top of the radiator showed 195 and he couldn't figure out why that was. When the engine temperature hit high "N", the car ran great. Very responsive and powerful. Now it
stays exactly in the middle of the "N" range. I am assume my driving it must have cleared all of the cobwebs out of the system and it now the engine temperature needle stays precisely in the middle of "N". Sounds good, but it is sluggish when it stays in the middle
of the "N" range. It runs like a cold engine runs, sluggish. When I drive it for a while and shut it off and wait a few minutes, the engine temperature needle will rise above "N" for a few minutes after I start it, it runs great, but then the engine temperature cools down to the middle of the "N" range and become more sluggish. I pulled the wire off of the Air Intake temperature sensor and the car starts a bit easier and idles a bit better and runs better at first, but runs a bit sluggish. I have ordered a NOS Bosch Air Intake
temperature sensor to replace what I currently have. I don't know if I have ever replaced it, but if I did, I am sure I did not replace with it with a Bosch brand sensor. Does anyone know if there is a thermostat that runs at a higher temperature than what is
in there now? Are there spark plugs which may run hotter that could be used? Could I drain the radiator fluid and use a lesser amount of anti-freeze? If I could get the temperature back at the high end of normal, it would be great. The car ran fantastic
when it did.

Maybe the wrong temperature sensor is installed.

Lots of things can make a car run hot, but pretty much only one can make it run cold - a thermostats that's stuck open, or not fully closing, or just opens at the wrong temp. You could take it out and test it in a pot of hot water.

Just read thru all of your previous threads. Here's a reply I posted on one almost a year ago that still looks relevant -

"Couldn't this be an auxiliary air regulator problem?

Steve - have you checked this out? - http://www.volvowiringdiagrams.com/v...%20Tracing.pdf"

Have you downloaded this manual yet? You really should as you should be going through the pertinent diagnostics step by step. That's probably the only way you're going to get this figured out.

Do you know how to check your auxiliary air regulator (aka AAV or auxiliary air valve) and have you done so? If not, you should. It's very simple and could be contributing to your problems if not functioning properly.

You should also test your coolant temperature sensor (Bosch part #0280 130 014 / Volvo part #241726), as I believe it could definitely be at least part of your problem. Do you have an ohmmeter? If not, you should get one.

I also believe you may have replaced you fuel pump multiple times with various pumps. Is the one currently in the car a Bosch #0580 464 007? If not, you should buy and install the one I believe I told you about a while back on a different forum that Redwood Chair might still have.

Note that 195 degrees at the top of the radiator sounds perfect. I don't know how your mechanic would have "known" that the coolant sensor showed 165 degrees, since, as you indicate, there aren't any actual degrees indicated on your gauge. What I strongly suggest you check is the temperature of the block at the rear, right about where the temperature sensor is for the gauge. Do you have an IR thermometer? If not, I recently bought a digital multimeter from Radio Shack that also has one of these built in. If you don't already have an ohmmeter, this one meter would take care of both things. On my '72 164E, the temperature at the top of the radiator was right about 195, while the temperature at the rear of the block would be at about 220. This was due to the block being "silted up", which these engines are prone to. This may not be causing your problems, but if you have this issue, its something you want to be aware of and want to have taken care of as soon as you can after getting it running better.

Lastly, have you done a compression test? You really should since, if you see a problem there, you may be chasing all of this other stuff for no good reason.

Oh, disclaimer time - I'm no mechanic, so hopefully someone more knowledgeable will chime in if I've given you any bogus advice.

I really hope you get your car running properly. Good luck!

Didn't read, but I would shoot a $30 HarborFreight infrared thermometer to confirm if true reading or bunkem.