A couple issues with my 96 850 Turbo sedan Topic is solved

Dave in Maine · Post by **Dave in Maine** » 26 Jan 2018, 10:43

I have a couple issues with my 96 850 turbo sedan and come to the experts here for advice. I have going-on 200k mi on it and have had a good amount of maintenance/repairs done this past fall so it would pass inspection, which it did.

Issue #1: anti-overheating. I live in Maine, where it gets cold. This morning it was 10F (-13C or so) and that's a lot warmer than some of the days around Christmas, when that was the high temperature. Long story short, when the temperature outside is lower than about 20F (-7C or so), the temperature gauge stays pegged on "cold" and the heater yields no heat. This is especially true when I'm driving on the highway. In the city and over 20F, the needle moves into the "normal" range and the heater yields heat. But, get on the highway and the needle sinks to "Cold" and the heater stops heating. One day, I drove about 60 miles (100km) on the interstate when the temperature was about -10F (-23C) and the needle never moved from "Cold". And there was no heat worth talking about.
So, we know the needle works and the heater works, but only in some warmer temperatures.
What's going on here? Bad thermostat?

Issue #2: burning black. This morning, I drove a short distance and noted a strong smell of burning, maybe oil. After running a little while the smell dissipated, but I also noted a black ring of soot on the rear bumper around the exhaust. A couple days ago, I had the car idling in the driveway and noted soot being deposited from the exhaust onto the snow.
How worried should I be?

Thanks in advance!

Teddy1975 · Post by **Teddy1975** » 26 Jan 2018, 10:53

Sounds to me like a bad thermostat for issue #1. A quick temporary fix could be to use a piece of cardboard and cover up half of your radiator until you can change the thermostat. Not sure about issue 2 though.

DeathRex · Post by **DeathRex** » 26 Jan 2018, 11:14

Yep #1 is thermostat staying open too much. #2 sounds like engine running rich, and when it's cold the engine is supposed to run rich until it warms up (what a choke accomplished back in the day). Might be that with engine not warming up, the ecu keeps the engine on rich, or it's taking longer to get to lean.

Post by **RickHaleParker** » 26 Jan 2018, 13:15

#1 Thermostat stuck open.
#2 Soot always means incomplete combustion, engine, campfire ect.

Fix #1 first, then see if #2 goes away.

Post by **erikv11** » 26 Jan 2018, 13:45

They all said the same thing, so do I, good advice here. I'd recommend Gates or Wahler for the thermostat.

Oly850 · Post by **Oly850** » 26 Jan 2018, 14:04

Issue #2 is because of issue #1 definitely. Get a good OEM thermostat that opens at a higher temp and flush out your cooling system, you may have more than a 50/50 mix of coolant. Covering up 1/2 the radiator may help too certainly on the freeway.

Post by **scot850** » 26 Jan 2018, 15:07

Volvo standard thermostat is a 90C opening one. Being a turbo they also tend to be affected by the cold more than NA's. Teddy's suggestion to fit some cardboard behind the grill is a good one. Here when it gets really cold (-20C and lower) I fit a piece of cardboard behind the upper grille on the turbo car to stop the intercooler freezing (even when moving!!). I zip-tie it to the back of the grille. Don't run this way at much above -5-10C. If you do, watch that temp gauge!!!

Neil.

Post by **wizechatmgr** » 26 Jan 2018, 16:06

#1 +1 on thermostat being the cause

The thermostat blocks coolant from being cooled in the radiator and recycled back to the engine. Lucky for you most (not all) fail open causing you to always cool the engine and as a result, no heat as that also comes off the coolant circuit. Its a rather easy driveway fix - but with the weather, you may want to find a small shop to do it. Shouldn't be more than a half hour labor. Sadly many shops round up to the next hour.

#2 is the catalytic converter getting overly hot because it is getting too much unburnt fuel - fix #1 and it too should go away. Do so sooner rather than later or you can melt that cat's internal core.

Post by **RickHaleParker** » 26 Jan 2018, 16:30

How worried should I be?

Worried enough that you don't procrastinate.

Dave in Maine · Post by **Dave in Maine** » 05 Feb 2018, 20:15

Didn't procrastinate - got a new thermostat installed today. While it seems the car is running better - temp wise - I'm going to have to wait until the next cold snap to see whether the fix really works. If I have heat the next time it's <10F and the engine isn't burning black, we're good.
I'll keep you posted.