Faulty aircon = coolant leak = overheating?

**kapowww** · 18th June 2014, 12:36 PM

When I test drove my P38 all was well as there were no leaks and no book symbol on the A/C. Obviously a couple of test drives don't really mean much as you can't possibly do enough real world testing. Anyway the day after I got it I changed some A/C settings and the dreaded book symbol appeared. It would appear a few minutes into driving on certain settings.

Then whenever I drove I'd lose a bit of coolant (up to 300mL at a time) and if I drove for over 30 minutes then I'd lose a whole lot more especially going uphill. Then it would start overheating and I read all the scary threads about head gaskets and new engines, etc.

Took it back to the roadworthy mechanic who fixed a couple of coolant leaks by replacing the radiator cap and heater hose.. Problem still happened after long drives and I couldn't tell there was less coolant until the next day. I kept topping it up and driving it short distances.

One day my wife finally took it for a drive and changed the A/C settings. Since she did that the evil book symbol hasn't appeared, and the coolant has not leaked one drop! No more overheating! Now.. I'm scared to change the A/C settings because I don't want it to leak again, and I don't want to jinx this good run haha.

Old settings: I would usually turn A/C off but seemed to happen with it on too, have the dash and feet blowers, and whatever temperature set.

New settings: A/C on, only the feet blowers, and I've tried a few different temperature settings with various outside temps (hotter than outside, colder than outside).

So what could the problem be? Is there a link between the A/C faulty book symbol and coolant leaking? Not sure if the colder Melbourne weather has helped but I've driven on slightly warmer days with no problems.

mike 90 RR · 18th June 2014, 03:46 PM

Originally Posted by kapowww

especially going uphill. Then it would start overheating

Symptoms of a blocked radiator....

Basically ... you have a old car.

1: You need to have the Radiator rodded or replaced.
2: The viscous fan needs to be checked for working.

Get this part of the cooling system up to date.

Cheers
Mike

**Hoges** · 18th June 2014, 04:54 PM

x2 as above ..plus
FWIW: The plenum chamber in the heating system has flap which moves in accord with temp settings. The (plastic) chamber "box" can get slightly out of shape over the years due to heat. This can cause the blend flap to bind, causing the blend motor to stall and resulting in a book symbol. For example, I get no book symbols during winter when the ambient air temp is less than 17 degC... yet, as the day warms up, the book symbol appears

because the flap gets jammed and won't cycle through its full arc... not saying this is what your issue is, but it's one of several which can cause problems.

coolant flows through the heating system all the time; it's the blend flap which determines the temperature... what colour coolant are you using in your engine?

EDIT: have a careful look at the front of the engine to see if you have any leaks around the water pump. Check for evidence of coolant leaks with an inspection mirror if necessary, around the rear of the heads and also around the head bolts for #1 cylinder (front LHS -passenger side)

**TheTree** · 18th June 2014, 05:12 PM

Hi

Also don't forget to check and replace RL7 in the fusebox if you have or have had the book symbol.

This should extend the life of your fusebox

Steve

**kapowww** · 18th June 2014, 06:32 PM

Originally Posted by Hoges

For example, I get no book symbols during winter when the ambient air temp is less than 17 degC... yet, as the day warms up, the book symbol appears

because the flap gets jammed and won't cycle through its full arc... not saying this is what your issue is, but it's one of several which can cause problems.

coolant flows through the heating system all the time; it's the blend flap which determines the temperature... what colour coolant are you using in your engine?

EDIT: have a careful look at the front of the engine to see if you have any leaks around the water pump. Check for evidence of coolant leaks with an inspection mirror if necessary, around the rear of the heads and also around the head bolts for #1 cylinder (front LHS -passenger side)

Mine used to do that but book symbol hasn't shown for weeks no matter the outside temp and it has reached 20 and also in traffic where other exhaust heat tends to bump up the temp.

Mine has red coolant. Not sure of the ratio to water and how sensitive a Rangie is to that.

Originally Posted by mike 90 RR

1: You need to have the Radiator rodded or replaced.

2: The viscous fan needs to be checked for working.

1. Yep I realised that and realise I'd probably have to replace the radiator. Been looking at the eBay ones. They any good?

Thing is I don't want to spend money on replacing that before spending money on fixing the leak in case it's something a lot worse.

2. Is that by doing the rolled up newspaper test? I did that and it's all good. I haven't checked to see if it turns on at the right times.

**kapowww** · 18th June 2014, 06:33 PM

Originally Posted by SteveFarmer

Hi

Also don't forget to check and replace RL7 in the fusebox if you have or have had the book symbol.

This should extend the life of your fusebox

Steve

Will do.

mike 90 RR · 19th June 2014, 08:03 AM

Originally Posted by kapowww

1. Yep I realised that and realise I'd probably have to replace the radiator. Been looking at the eBay ones. They any good?.

I prefer copper core radiators ... however tho, anything will be heaps better than what you have.

Originally Posted by kapowww

Thing is I don't want to spend money on replacing that before spending money on fixing the leak in case it's something a lot worse..

Unfortunately ... You cannot identify "something a lot worse" until you eliminate the radiator .... If you don't, then it is guaranteed that you will overheat the motor and then your up for 4 to 6k for a reco motor.

Originally Posted by kapowww

2. Is that by doing the rolled up newspaper test? I did that and it's all good. I haven't checked to see if it turns on at the right times.

All sorts of tests available .... Another way is to compare the resistance of your viscous to a new 1 ...

Cheers
Mike

**Nomad9** · 19th June 2014, 08:37 AM

Hi Lapowww,
The two P38's I've had have both had green coolant in them.

**TheTree** · 19th June 2014, 08:45 AM

HI

You can always go this route

http://www.aulro.com/afvb/p38a-range...m-upgrade.html

Steve

**TheTree** · 19th June 2014, 08:47 AM

HI

I believe the Bosch models had red coolant, but if you do get a copper core radiator you MUST use green coolant

Steve

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