safety first...attempting to stopping a 20+ yo piece of rotating plastic running @ 100 mph+ at the outer edge may not turn out so well. Had i done this newspaper test the day before my fan failed i probably would have been seriously injured at worst, or caused further distress to the fan blades ready for them to shatter the next day
Datatek
Well-Known Member
The general idea is it shouldn't stop, it should shred the paper. If the viscous has failed, the fan stops easily.
P38 Monkey
Well-Known Member
So, confident that the cooling system was sorted, off I drove.
After about 15 miles of cool runnings, instant and major overheating: the header tank had decided to disgorge its contents and more.
No burst pipes, so I took out the header tank to check it for leaks.
The radiator bleed pipe connector in the header tank neck was blocked with what looks like silicone sealer swarf - see photo.
I cleaned it out with a drill bit. The triangular piece in the photo is a paint fleck.
The (inaccessible) metal pipe that extends into the header tank remained blocked, so I used a tyre pump with the football inflation bit, and the pipe spat out a small piece of "rubber" - see photo.
Is that the smallest thing that has ever brought a mighty 4 litre V8 to its knees?
I am assuming that the pieces are silicone sealer swarf, dislodged when the cooling system was flushed recently.
Has anyone had this problem before? Are they silicone sealer bits, or some disintegrating critical component??
The worry is that there are more bits in the system, waiting to travel round to the header tank...
But at least I now know how to fix it.
I remain impressed by the wide variety of faults that the P38 is capable of dumping on the unsuspecting owner.
After about 15 miles of cool runnings, instant and major overheating: the header tank had decided to disgorge its contents and more.
No burst pipes, so I took out the header tank to check it for leaks.
The radiator bleed pipe connector in the header tank neck was blocked with what looks like silicone sealer swarf - see photo.
I cleaned it out with a drill bit. The triangular piece in the photo is a paint fleck.
The (inaccessible) metal pipe that extends into the header tank remained blocked, so I used a tyre pump with the football inflation bit, and the pipe spat out a small piece of "rubber" - see photo.
Is that the smallest thing that has ever brought a mighty 4 litre V8 to its knees?
I am assuming that the pieces are silicone sealer swarf, dislodged when the cooling system was flushed recently.
Has anyone had this problem before? Are they silicone sealer bits, or some disintegrating critical component??
The worry is that there are more bits in the system, waiting to travel round to the header tank...
But at least I now know how to fix it.
I remain impressed by the wide variety of faults that the P38 is capable of dumping on the unsuspecting owner.
Looks like a PO has been a bit careless with sealant, similar done on a sump gasket can destroy an engine
when, the excess sealant blocks the oil pick up strainer.
P38 Monkey
Well-Known Member
Actually that’s sort of reassuring to hear.
As with all previous owners, my PO caused a lot of damage…. I imagine the guy’s toolkit was a pair of mole grips and a claw hammer…
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P38 Monkey
Well-Known Member
OK, I'll grant that they are useful in carpentry - saves all that twiddling to fasten wood screws - just bang them straight in.And prey tell what's wrong with a hammer
My P38 PO clearly believed that an alternative to nyloc nuts was to cross-thread plain nuts. Stops 'em from coming loose.
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All good mechanics have a should have nice selection of hammers. Useful in all applications
Yes i had this. Traced to a string of silicone sealant in the top of the radiator, ever so often it would get stuck in the outlet pipe.. caught it on a bad day and managed to fish it out with a bit of hooked wire.
P38 Monkey
Well-Known Member
Glad it's not just me, then.
Silicone sealant - the bodger's delight...!!
Just went for a quick run - all seems OK.
Any excuse to drive my P38 - I feel like a kid with a new bike...
P38 Monkey
Well-Known Member
I found this Youtube explanation of the viscous coupling really useful.
There are also some good videos on the newspaper test - not as scary as it sounds.
I thought you stuffed a rolled up Sunday Times straight into the fan, but it's more gentle than that....
There are also some good videos on the newspaper test - not as scary as it sounds.
I thought you stuffed a rolled up Sunday Times straight into the fan, but it's more gentle than that....
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If you're sure which way it's rotating, it can't hurt you but, I wouldn't risk it either, a newspaper could also be
dangerous if you poke it the wrong way.
Also known as the swedish nut lathe and a brummie spanner, the latter also known as Land Rover special tool LR-001-001.
P38 Monkey
Well-Known Member
The finger check is OK if the coupling is working correctly or has failed "free-wheeling", but if it has failed "stuck" there might be bits of finger detaching from their owner.
I favour the "slight drag and not free-wheeling when cold and all switched off" check.
As to which newspaper to use - be careful what you are seen to employ:
The Daily Mirror is read by people who think they run the country. The Guardian is read by people who think they ought to run the country. The Times is read by the people who actually do run the country. The Daily Mail is read by the wives of the people who run the country. The Financial Timesis read by people who own the country. The Morning Star is read by people who think the country ought to be run by another country. And The Daily Telegraph is read by people who think it is.
Sun readers don’t care who runs the country as long as she’s got big tits.
Yes, Minister. Or possibly Yes, Prime Minister. One of Sir Humphrey's excellent explanations.
P38 Monkey
Well-Known Member
The alarming event of the blocked radiator bleed pipe had left the P38's cooling system full of plain water more or less, so I drained the radiator (which releases 4 litres) and filled via the header tank with OAT pink concentrate. Having learnt a great deal from the various postings above, I bled the radiator (engine off) by squeezing the top hose whilst holding my finger over the little hole in the header tank neck.
Air bubbles out of the metal pipe in the header tank, and then sucks coolant back up the pipe. Repeat until no further bubbles appear.
I now know what a clear bleed pipe feels like: it is easy to blow air through it.
A scientific approach shows that using my Ring 6000 tyre pump (the football inflation adapter) at the radiator end of the pipe, blows air through at a steady 5 psi.
Putting a finger over the little hole while blowing air down the pipe shows no change in that pressure.
Job done, cool runnings, and many thanks for all the advice - greatly appreciated.
Air bubbles out of the metal pipe in the header tank, and then sucks coolant back up the pipe. Repeat until no further bubbles appear.
I now know what a clear bleed pipe feels like: it is easy to blow air through it.
A scientific approach shows that using my Ring 6000 tyre pump (the football inflation adapter) at the radiator end of the pipe, blows air through at a steady 5 psi.
Putting a finger over the little hole while blowing air down the pipe shows no change in that pressure.
Job done, cool runnings, and many thanks for all the advice - greatly appreciated.
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