850 engine overheating

CARPMAN · Jul 9th, 2009, 19:32

We were told that my friends 850 cylinder head gasket had gone because the engine was overheating and boiling over in traffic. This has been happening for some time. We have taken the thermostat out but it still does it.
This diagnosis was arrived at because the water hoses became pressurised so the garage says.
It also failed the MOT on lambda oxygen readings being to lean. we have
replaced the engine with a good second hand lower mileage unit but to our dismay the same overheating problems are still there. Has anyone got any ideas as to what could be causing this.

ShadeTek · Jul 9th, 2009, 19:36

It could be a blocked radiator or collapsed hoses?

lab_rat835 · Jul 10th, 2009, 02:25

the 20v engine also takes ages to get all theair out the system i had to do about 100miles with the cap loose till mine was right

stevesR · Jul 10th, 2009, 07:36

Quote:

Originally Posted by ShadeTek

It could be a blocked radiator or collapsed hoses?

As ShadeTek says it sounds like a knackered radiator.

Blue 8 · Jul 10th, 2009, 07:47

As above faulty rad

sunjester · Jul 10th, 2009, 08:19

My 850R suddenly overheated a couple of weeks ago and blew most of coolant out of expansion tank.
AA guy also diagnosed head gasket as his pressure test showed the cooling system was pressurised (coolant systems run pressurised anyway) but his block test did not show a failure. Pump is OK so he was definate it was the head gasket.

I was going to do this myself but speaking to a mechanic at the local Volvo dealer he suggested the thermostat. He said Volvo run the engines quite hot and the slightest problem in the cooling system will trigger this overheating problem. He also said if the car starts OK on all 5 straight away it's unlikely to be head gasket - mine does.

As that was a much cheaper option, I replaced thermostat plus the expansion tank cap and now all seems OK again.
I bought a block test kit, and tested twice (once after a 20 mile run) and engine passed this completely so I'm confident the head gasket is OK.

The hoses still seem to be pressurised, but as I didn't check before the problem started I don't know if it is at a normal level or excessive. I'm a bit suspicious of the small hose from the thermostat housing to the expansion tank and think there may be a partial blockage there.

It seems that diagnosing a head gasket failure is almost the easy option for even experienced people when dealing with these engines.

KBB · Jul 10th, 2009, 19:02

Carpman. You say it boils over in traffic. If it is ok on a run then I would be looking at the electric radiator fan. It is required when the vehicle is traveling slow or static as their is no air flow over the radiator. Dose the fan come on when static?

CARPMAN · Jul 11th, 2009, 07:00

Yes KBB the fan does come on when the car is stationary. When I feel the hoses they are rock hard. I can see that the water is circulating OK. And I know the cylinder head gasket has not gone. The raidiator has been flushed out and is not blocked. Also have fitted a new green expansion cap.Thermostat also removed.

I must say Im baffled it seems reading some of the posts on the forum that this is a common fault.

Jod T5 · Jul 11th, 2009, 10:32

Quote:

Originally Posted by CARPMAN

Yes KBB the fan does come on when the car is stationary. When I feel the hoses they are rock hard. I can see that the water is circulating OK. And I know the cylinder head gasket has not gone. The raidiator has been flushed out and is not blocked. Also have fitted a new green expansion cap.Thermostat also removed.

I must say Im baffled it seems reading some of the posts on the forum that this is a common fault.

How can you tell the water is circulating "ok"....
If the pipes are rock hard then i would also think there is some obstruction..Ok, they are supposed to be hard but not that hard....
Do the pipe soften when cold?.

The emmissions will sort itself when the temperature is fixed...

Jod

Chris_Rogers · Jul 11th, 2009, 11:51

"I can see that the water is circulating OK"

How?

If you have replaced everything else, there are no obstructions and the head gasket is OK then this only leaves a worn water pump.

Jul 9th, 2009, 19:32	#1
CARPMAN Junior Member Last Online: Nov 20th, 2012 16:19 Join Date: May 2009 Location: lincoln	850 engine overheating We were told that my friends 850 cylinder head gasket had gone because the engine was overheating and boiling over in traffic. This has been happening for some time. We have taken the thermostat out but it still does it. This diagnosis was arrived at because the water hoses became pressurised so the garage says. It also failed the MOT on lambda oxygen readings being to lean. we have replaced the engine with a good second hand lower mileage unit but to our dismay the same overheating problems are still there. Has anyone got any ideas as to what could be causing this.

Jul 9th, 2009, 19:36	#2
ShadeTek Premier Member Last Online: Apr 20th, 2024 19:38 Join Date: Dec 2002 Location: Renfrewshire View Photos By: ShadeTek	It could be a blocked radiator or collapsed hoses? __________________ Tek-Emo Villis Emo Bis V70 SE NAV 1.6 D2 2015MY POWERSHIFT, D4162T, 93000miles, RED. /VOL FCR/PEPER OBD2/Acron 9135 OBD2/L.E.D Flasher/VDASH/ANCEL BA301/Topdon Top Scan

Jul 10th, 2009, 02:25	#3
lab_rat835 Junior Member Last Online: Nov 9th, 2009 18:29 Join Date: Jun 2009 Location: northampton	the 20v engine also takes ages to get all theair out the system i had to do about 100miles with the cap loose till mine was right __________________ 1995 850 2.0 20v green estate know as "the volvo of love" mobile mechanic

Jul 10th, 2009, 07:47	#5
Blue 8 Premier Member Last Online: Aug 13th, 2015 17:06 Join Date: Aug 2008 Location: Medway Towns	As above faulty rad __________________ Stay away from negative people they have a problem for every solution. Ruby-red pearl 854 GLT 2.5 20v 62k.....Andy

Jul 10th, 2009, 08:19	#6
sunjester New Member Last Online: Jan 17th, 2017 15:45 Join Date: Feb 2009 Location: Gateshead	Overheating... My 850R suddenly overheated a couple of weeks ago and blew most of coolant out of expansion tank. AA guy also diagnosed head gasket as his pressure test showed the cooling system was pressurised (coolant systems run pressurised anyway) but his block test did not show a failure. Pump is OK so he was definate it was the head gasket. I was going to do this myself but speaking to a mechanic at the local Volvo dealer he suggested the thermostat. He said Volvo run the engines quite hot and the slightest problem in the cooling system will trigger this overheating problem. He also said if the car starts OK on all 5 straight away it's unlikely to be head gasket - mine does. As that was a much cheaper option, I replaced thermostat plus the expansion tank cap and now all seems OK again. I bought a block test kit, and tested twice (once after a 20 mile run) and engine passed this completely so I'm confident the head gasket is OK. The hoses still seem to be pressurised, but as I didn't check before the problem started I don't know if it is at a normal level or excessive. I'm a bit suspicious of the small hose from the thermostat housing to the expansion tank and think there may be a partial blockage there. It seems that diagnosing a head gasket failure is almost the easy option for even experienced people when dealing with these engines.

Jul 10th, 2009, 19:02	#7
KBB Master Tech Last Online: May 18th, 2020 10:57 Join Date: Dec 2006 Location: On Contract Dubai Automotve Technical Academy	Carpman. You say it boils over in traffic. If it is ok on a run then I would be looking at the electric radiator fan. It is required when the vehicle is traveling slow or static as their is no air flow over the radiator. Dose the fan come on when static?

Jul 11th, 2009, 07:00	#8
CARPMAN Junior Member Last Online: Nov 20th, 2012 16:19 Join Date: May 2009 Location: lincoln	Yes KBB the fan does come on when the car is stationary. When I feel the hoses they are rock hard. I can see that the water is circulating OK. And I know the cylinder head gasket has not gone. The raidiator has been flushed out and is not blocked. Also have fitted a new green expansion cap.Thermostat also removed. I must say Im baffled it seems reading some of the posts on the forum that this is a common fault.

Jul 11th, 2009, 11:51	#10
Chris_Rogers VOC Member Last Online: Apr 10th, 2017 16:55 Join Date: Jan 1970 Location: South Kent Coast	"I can see that the water is circulating OK" How? If you have replaced everything else, there are no obstructions and the head gasket is OK then this only leaves a worn water pump.

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