I'm having a number of cooling system issues with my 1996 960.

First, the coolant was slowly disappearing, there were no apparent leaks, this went on for a few months. Then heater hose blew. A week later my wife took the car to Las Vegas on a very hot day and called me on the way to say that the temperature gauge was erratic, bouncing between 1/2 to full redline. She pulled over, everything seemed fine and she topped off the coolant level and continued on the trip without incident, other than the gauge flipping out sometimes. When she got back I replaced the coolant cap and thermostat and watched the temp gauge when I drove. The gauge seemed slow to get moving at all and never went above 1/2. Within a few days, the side of the radiator blew out. After researching the Volvo radiators I decided to put in an all metal one. After a few weeks of searching, I got the ONLY all metal one I could find and it was a tight squeeze to get it in. I had to slightly hammer the little 1/8" inch flange along the lower sides to get it to fit, I also had to trim the plastic fan shroud for the slightly wider radiator. I was concerned that anything rubbing on the radiator might wear a hole in the soft metal. The next week I decided to check out the car before heading out on a weekend trip and noticed coolant on one side of the radiator. It turns out that about six inches of the welded seam was leaking, BUT, it was not leaking anywhere near where I bent the flange. My guess is that the radiator was defective but since I "modified" it I decided to just eat my losses and put in an OEM Nissans plastic/aluminum radiator. It took a few weeks to get it and went in without incident.

A few days later, on a cold morning, the car wouldn't start. After researching on the volvo boards I found out how to get it started and decided to do an "Abe Crombie tune-up" to clean off the valve stems. The Tune-up calls for driving in Low at 55 MHP and 4500 RMP for 5 minutes. Well, I don't know about anyone else's 960, but in low drive, my car goes about 35 MPH at 4500 RPM. So, I did this, while carefully watching the temperature gauge to make sure the car didn't overheat at this low speed with the lower airflow. After about 4 minutes... the car overheated. The temperature gauge never went above 1/2 way.

Today, I disconnected the temperature sender and hooked it up to an ohm meter, I also shunted the wire going to the gauge with a 1k resistor. I then started the Volvo and measured the resitance while taking temperature readings off of the thermostat housing. The temp sender has a fairly linear reading but is off about a factor of 5 from what's in the Chilton manual. I then hooked up a variable resistor to the gauge wires and could get the gauge to move in the lower 1/2 range, but never above.

Ok, so here are my questions:

Does it make sense that the car would overheat driving at 35MPH and 4500 RPM?

Does anyone know what the specific readings should be for the temp sender? Is the Chilton manual correct? Do all the 199x's Volvos use the same temperature sender?

Does it sound like the temperature gauge is bad, too.

Can one Volvo have so many cooling problems in just a few months???

I'm starting to regret buying my first used Volvo. HELP!!!

Fletch

Since replacing the coolant temperature sender the 960 has been working perfectly! My only guess is that the bad temperature sender really messed up the fuel/air mixture and fouled the plugs and gunked up the whole system and was causing the smoke. We drove the car for a number of hours under different driving conditions on Christmas without the slightest hiccup or out of the ordinary puff of smoke. I still suspect that the temperature gauge is bad and won't display readings above 1/2. I'll have to do a little more testing to verify that.

Thanks for all your advice in this board, it's been a GREAT help.

Fletch

couple of thoughts here...

1. it sounds like something is up with the cooling system...
2. check you whavent got a brake draging of similar..
3. think it through and work methodiacally...and do easy things first...
i would defiantely change the thermostat and check the water pump, water pump belt and rad fan...

I'm not sure if we've ever discussed a water pump failure in the 960 series, but one would wonder if this might be contributing to the problem, considering you've changed out just about everything else, save for the hoses. I understand that these pumps can have subtle way of failing with some seepage, but especially increased play beginning in the pump. If it's tight you should be able to take ahold of it and attempt to 'wiggle' it with little play in it. If it's going south, I would wonder what driving symptoms it might manefest.

Just a thought...
--
John Shatzer, '97 V90 @ 92K; 92 965 @ 106K

Well, the new temperature sender is in and I drove it a little bit. The temperature gauge seems more normal (went a little higher in the hot range but moved up quite fast this time).

But I came back when I noticed a lot of smoke coming from the exhaust. Lately, there's been a LOT of smoke when the car first starts up in the morning. 140,000 miles! Another project for another day :(

Fletch

Fletch,
Does your car have a rough idle? Does it shake a lot while idling? When you turn it on there should be no shake, you should not even be able to tell the engine is on. What color is the smoke? What does this smoke smell like? Has your car been burning oil?

Brandon

I'm using a 50/50 mixture with only Prestone coolant. The thermostat is just a few weeks old. I don't think the coolant is leaking out anymore... but it's hard to tell because the car has not run long enough to get a good indication.

I don't think the problems are related to a head gasket leak because I think I would feel the pressure increase in the radiator hose early on.

I just went out and bought a new temperture sender. As I drove up the hill to my house I could see the temperature increasing (the gauge moved to the middle area). Just as I pulled into the driveway I saw a shot of steam come out from under the hood. I left the engine running since the steam stopped and I popped the hood. The fan wasn't even running. I know the fan and relay works from my earlier variable resistor test.

I can tell by hooking an ohm meter up to the new temperature sender, and taking a reading at room temperature, that the old one was reading WAY to low. Hopefully, this will fix my problem. I still suspect that the temperature gauge is bad.

When I first got the car I flused the fluid with prestone. Dont use that stuff its not phosphate-free. This can corode engine parts. It only takes a little bid of volvo coolant to cause this effect. Even if you drained the fluid out you would need to flush the cooling system with water. Flush it and add Volvo or a Phosphate-free coolant. Spending a few extra bucks now will pay off in the long run. I have 100k on my 96 and I have learned a few things from this car. It is very tempermental ask the guy that posts as 34N118W, or Abe crombie, or Stever Ringlee, and John aka Shatz

Brandon

Fletch,
Dont worry there are a few things that can be wrong. On my way to Sacramento I had the car going at 4500=115 mph in Drive for about 20 minutes. I was the only one on the freeway so I figured I would give it a try. That car has such a good cooling system it should stay in the middle no matter where you go and how hard you run it.

1. What type of coolant do you use. If you mix coolants like OE volvo (The blue coolant) with prestone, when the two get hot they get thick and plug up the thermostat thus letting the car over heat. I have always used distilled water and the Blue volvo coolant. I is $15 a gallon but it works. I have heard that other coolants are bad for the cooling system.

2. Your thermostat might be stuck mid way. Meaning that under hard driving conditions your car is not really cooling itself as well as it could. Its easy to replace. all you need is a torx rench and the $10 thermostat from the dealer.

3. are you still loosing coolant? IF so you could have a head gasket problem. Open your expansion tank after the car has hit normal opperating temperatures. Does the fluid spew out as if under really high ammounts of pressure? While doing this look at the rear of the engine and check that those two hoses arent leaking. This can also cause a leak of fluid.

One last thing. Check your engine oil level is it low? This helps cooling a little bit. Not a significant thing but still someting worth looking. Does your cooling fan work? This also helps cooling.
If I were you I would replace my coolant and thermosat right away. Then Try the abe crombie tune up. When you do this leave your car in drive till you hit over 30 mph then put it in low. This locks your car into 2nd gear and not 1st. Hope this helps. please feel free to ask questions.

Brandon 96 960

Take a hard look at the head gasket. Have someone do a cooling system pressure test to find out if exhaust gases are pressurizing the cooling system.

Steve,
I know a blown head gasket would allow exhaust gasses to going into the fluid but when I had a blown head gasket my car did not overheat once. I think he is dealing with 2 differnt types of coolant mixed in the cooling system. Prestone and volvo coolant dont mix very well, and they cause the car to over heat under hard conditions.

I had a 240 many years back. It had a cracked head courtesy of an idiot previous owner. It ran hot before the crack was fixed, as well as misfired upon initial startup in the morning. Also, it blew large quantities of steam out the exhaust in the mornings.

I would put my money on coolant entering the combustion chamber somehow.

The nice thing about a cooling system is that the components are not terribly exotic and are easily replaced, incuding the water pump. Be sure you know that all components are properly working before looking for zebras.
--
John Shatzer, '97 V90 @ 92K; 92 965 @ 106K