1998 4.6 P38 Overheating - Losing coolant

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chrispiec

Active Member
Posts
183
Hi Guys,

my car has recently started overheating. It did it last weekend when i was reversing my boat in the drive but i just thought it did this because i was in low gear and was reversing back and forth a lot to get it into the drive. i let it cool then topped up the coolant. It was fine all last week driving back and forth to work etc. No overheating issues at all until saturday just there it overheated again whilst i was towing my boat in hi gear at about 30mph. Stopped let it cool then topped up with water then slowly drove off and everything was fine again. Needle sat right in the middle. Took boat down to water then pulled boat out of water then took boat home and everything was fine no overheating. I then was driving uphill and could here misfiring and then saw the temp had rocketed up to red. i let it cool then topped up with more water and then checked the expansion tank for bubbles and it was clear and i checked the oil filler cap and dip stick for any gunk and it also was fine.

Basically i dont think/hope it is the head gasket. Anyone got any ideas?

I also bled through the coolant system and topped up last night but it then overheated whilst at 70mph on the motorway. I stopped before it hit the red and checked expansion tank and it was empty.

Anyone got any ideas? and sorry for such a long post!
 
If it was the headgasket would i not be getting dampness in the oil and contamination in the expansion tank?

I drove to work to work this morning and the temp was fine and the coolant seems fine. Hasn't reduced etc.
 
im going to run it on petrol only over the next few days and see if i get any overheating problems.

Anyone got any other theories. I checked coolant and oil and both appear to be clear from contamination of one another. There are no bubbles in the coolant either. I spoke to my gas bloke and he said that if the lpg condenser is duff it could cause overheating due to high pressure.

Im getting it pressure tested tomorrow and have been told to bypass the condenser to rule that out or show it up as the culprit.

Also i forgot to say that apart from the overheating issue the car is running fine idles fine, fast idles fine and drive fine even on a cold start in the morning. That is why im doubtful of head gasket or slipped liner.

Any comments etc much appreciated.
 
you may wish to run it into your local MOT testing Station & have the guys there put their Exhaust Gas analyser probe into your Expansion tank.

Any "Loose" hydro-Carbons (From Exhaust gasses) showing up will point you in the right direction... The EGA is extremely senitive & should show a very low reading / non at all if yer Head Gaskets are OK & up to Spec
 
Radiator hoses like all rubber can gradually disintegrate becoming porous and allowing evaporation under pressure. Or the aluminium clamps at the ends of those hoses can start to cut in to the rubber and then leak. Either can be dangerous as could lead to "sudden catastrophic failure", i.e. bursting. Water jacket around the engine can leak. This one is sneaky and hard to catch, pressure test may help. Seal around water pump can leak or the pump could just be weakening. And there are little plugs at the bottom of the engine case, as in the picture, and as you also see, not all leaks drip, some just seep so there's no puddle under the car at least at first. Note how the coolant stains are a tip-off. Alternatively you may have airflow problems in the rad. Which means check fans are running, check for clogging and debris in the fins and finally for clear waterflow through the pipes which can clog just like arteries.

I'm concerned that it ran in to the red that first time before you noticed as that tends to cook the head gaskets and do all sorts of mischief. If you've the time perhaps you'll consider having the heads off and checking the condition of the gaskets. Might as well change them even if you got away without needing a skim or liners etc. Good luck!
 

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rasheed said:
Radiator hoses like all rubber can gradually disintegrate becoming porous and allowing evaporation under pressure. Or the aluminium clamps at the ends of those hoses can start to cut in to the rubber and then leak. Either can be dangerous as could lead to "sudden catastrophic failure", i.e. bursting. Water jacket around the engine can leak. This one is sneaky and hard to catch, pressure test may help. Seal around water pump can leak or the pump could just be weakening. And there are little plugs at the bottom of the engine case, as in the picture, and as you also see, not all leaks drip, some just seep so there's no puddle under the car at least at first. Note how the coolant stains are a tip-off. Alternatively you may have airflow problems in the rad. Which means check fans are running, check for clogging and debris in the fins and finally for clear waterflow through the pipes which can clog just like arteries.

I'm concerned that it ran in to the red that first time before you noticed as that tends to cook the head gaskets and do all sorts of mischief. If you've the time perhaps you'll consider having the heads off and checking the condition of the gaskets. Might as well change them even if you got away without needing a skim or liners etc. Good luck!
Click to expand...

Completely Aggree with Rash, you could go & give it a right good FLUSH OUT as well

Someone posted on here before (Steve I think) he Weighed his OLD Rad & then Weighed his new one .. the difference was about 5 Kgs!!!!.. so he had 5 Kgs of CRUD sitting in the bottom of his Rad!!!!! Makes you think what the Water Ways are like then don't it!!!
 
could a faulty vaporizse/condenser be causing me these overheating issues?

Should i bypass it and just run on petrol to confirm this?
 
well lastnight i drained coolant, bypassed the vaporiser and filled and bled it through. I then got engine up to normal running temp then took it for a 10min run on the motorway and gave it a good boot up 70-80 under hard accelerating etc and then back to my house checked levels and e verything seemed ok. No loss of coolant. Heaters are blowing hot air fine.

Still nothing in the oil or the coolant. Im getting it pressure tested tonight as the garage cancelled last night. So im going to see what shows up. Im hoping i have a duff vaporiser and by bypassing it will show it up.

Anyone got any words of wisdom for me?
 
Right just back from garage and the car passed a pressure test. Put 10bar into it and left it for 10mins. No leaks and no loss of pressure.

How can i check if the vaporiser is actually the cause before buying a new one?
 
It seems to be working fine. The reason im suspecting the vaporiser is that recently my car was running rough on lpg, misfiring etc.

The farm seems to be functioning correctly although upon checking the other day a cannot remember ever seeing my condensor fans running. When should these power on? Also i found a lose connection hanging down behind the grille. A cable not connected to anything. I dont know where it goes but will have the grille off this weekend to see if i can locate the plugs destination.
 
chrispiec said:
It seems to be working fine. The reason im suspecting the vaporiser is that recently my car was running rough on lpg, misfiring etc.

The farm seems to be functioning correctly although upon checking the other day a cannot remember ever seeing my condensor fans running. When should these power on? Also i found a lose connection hanging down behind the grille. A cable not connected to anything. I dont know where it goes but will have the grille off this weekend to see if i can locate the plugs destination.
Click to expand...


The aircon condensor fans come on according to pressure in the aircon system, I believe on the petrol engine (but not the diesel) the Engine ECU can also operate the fans based on engine temperature. They rarely operate.
 
That's good coz I rarely see them on! Ha ha!

Jus did thirty mins of motorway driving and no overheating issues! Levels fine, hot air out of heaters, no oil in coolant and no coolant in oil!
 
Well I've had the heaters up full in order to give me good warning incase I running out of coolant not had aircon on much at all! It never gets that hot here! Altho I do have the aircon switch on the hevac unit set so the light is not on! Why do you ask J?
 
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