P38A Overheating now and again

Sonnycbr · Jan 30, 2022

Hello again, about 3 months ago I was out and about in the car and all of a sudden temp gauge shot up. I pulled in, turned engine off for about 10 minutes and it then drove fine.....until today. I've been out and when I reversed back onto the drive I saw a trail of liquid from the front of the car, coolant. I've replaced the coolant and all seems fine but I'm concerned about long drives now. Could it just be the thermostat, or is that too simple?
Car is a 2000 P38 4.6 petrol, Bosch engine.

Datatek · Jan 30, 2022

Sonnycbr said:
Hello again, about 3 months ago I was out and about in the car and all of a sudden temp gauge shot up. I pulled in, turned engine off for about 10 minutes and it then drove fine.....until today. I've been out and when I reversed back onto the drive I saw a trail of liquid from the front of the car, coolant. I've replaced the coolant and all seems fine but I'm concerned about long drives now. Could it just be the thermostat, or is that too simple?
Car is a 2000 P38 4.6 petrol, Bosch engine.

I take it it's your P38 4.6?
First thing to look at IMO is the viscous fan. Thermostat, water pump, and being a V8 HGF are also possibilities.

tomcat59alan · Jan 30, 2022

Sonnycbr said:
Hello again, about 3 months ago I was out and about in the car and all of a sudden temp gauge shot up. I pulled in, turned engine off for about 10 minutes and it then drove fine.....until today. I've been out and when I reversed back onto the drive I saw a trail of liquid from the front of the car, coolant. I've replaced the coolant and all seems fine but I'm concerned about long drives now. Could it just be the thermostat, or is that too simple?
Car is a 2000 P38 4.6 petrol, Bosch engine.

Get it up to temperature and see if you can see where it was leaking from.If it was up to temperature have you checked the fan,see if you can stop it with a rolled up newspaper.

Datatek · Jan 30, 2022

tomcat59alan said:
Get it up to temperature and see if you can see where it was leaking from.

Good point, I assumed the overflow from the expansion tank

kermit_rr · Jan 30, 2022

Also check your radiator for external blockages that could restrict air flow

Sonnycbr · Jan 30, 2022

Datatek said:
Good point, I assumed the overflow from the expansion tank

Sorry about that, it was all from the expansion tank.

kermit_rr · Jan 30, 2022

Was the top hose hard? Could just be a dead cap

Rubberknees · Jan 30, 2022

use one of the kits to check water for HGF

kermit_rr · Jan 30, 2022

Rubberknees said:
use one of the kits to check water for HGF

You mean to check for exhaust gases

Rubberknees · Jan 30, 2022

kermit_rr said:
You mean to check for exhaust gases

Sure do and where do the gasses come from? A cracked head or HGF

kermit_rr · Jan 30, 2022

Rubberknees said:
Sure do and where do the gasses come from? A cracked head or HGF

Yep or cracked block.. the the liquid doesn't say which

Rubberknees · Jan 30, 2022

kermit_rr said:
Yep or cracked block.. the the liquid doesn't say which

Either way Mega problems if it's positive

kermit_rr · Jan 30, 2022

Rubberknees said:
Either way Mega problems if it's positive

Sounds like that would be a pretty negative thing to me

Rubberknees · Jan 30, 2022

kermit_rr said:
Sounds like that would be a pretty negative thing to me

Ooooooooooooooh kermie

Sonnycbr · Feb 3, 2022

Rubberknees said:
use one of the kits to check water for HGF

Did that and liquid stayed blue. Just to be sure I stuck the test beside the exhaust and it went yellow. Don't know where that leaves me but at least I know it'll not be going to the knackers yard....yet!

tomcat59alan · Feb 3, 2022

Sonnycbr said:
Did that and liquid stayed blue. Just to be sure I stuck the test beside the exhaust and it went yellow. Don't know where that leaves me but at least I know it'll not be going to the knackers yard....yet!

Have you checked the fan? If it's ok remove the radiator , flush the system check the condition of the cooling vains and check the thermostat.

Henry_b · Feb 3, 2022

Fan
Thermostat
Rad cap

Process of elimination

dubbleRR · Feb 3, 2022

Henry_b said:
Fan
Thermostat
Rad cap

Process of elimination

Water pump blades slipping on the shaft..or breaking off...

romanrob · Feb 4, 2022

First of all the air gap probably got screwed up when the temp spiked (unless you refilled after that). Dumping coolant can just be a function of that, it doesn't have to be a major problem.... Then you have the fan (newspaper/ water pump (is the coolant coming through the bleed hose to the expansion tank when you remove the cap) or maybe the thermostat - but for me, and I messed around with all of those things, before finally replacing the rad.... You cd try back flushing the rad to see it it helps, but if any PO has ever put additive in the rad it most likely will be f***D. I did a post mortem on my old rad and half the galleries were completely clogged, so the ram air does not cool the rad as it should (and in that case the fan won't either, when it kicks in). That showed up as occasional overheating in slow traffic situations. You lose nothing from a good back flush fnar fnar

kermit_rr · Feb 4, 2022

A lot of people get concerned that the bottom of the v8 radiator is stone cold pointing to the thermostat not opening, but it's cold because the radiator is working properly, the thermostat will be opening otherwise you'll have big problems pretty quick

P38A Overheating now and again

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Think outside, no box required.

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