Hot PAS

[halcyongriff500]

After engine work on my 2001 Chim 450, the engine people said the PAS had failed during the test drive – suggesting it needed a new pump. Perversely the PAS was working when I collected the car, no whine from the pump, but I found that the fluid level was low. After topping-up the fluid the PAS seemed to be ok. After a few weeks I took it out for a drive when the steering became progressively heavier until the power assistance disappeared completely, this was accompanied by a hot smell – engine temperature normal. The fluid level was fine, my return journey was 25 miles, no power assistance until I was almost home when it returned. On a later 3 mile drive the PAS worked ok but was accompanied by the hot smell, again no noises from the pump. On checking the PAS pump had become very hot as had the PAS fluid – there was a misting on the reservoir under the cap suggesting the fluid had boiled [the cause of the hot smell]?
I am inclined to change the PAS fluid to see what happens – never done this before, is the fluid drained with the engine running?
Any thoughts? Stay safe!

[BIG DUNC]

Strange.

I wouldn't change it with the engine running.

Nothing to loose by draining and refilling the system, although I am struggling to see how the fluid could have caused this.

[Steve_D]

What colour is the fluid?
If it is brown it has overheated and must be binned. If it is still nice and red/pink then I cant see how the fluid alone could be causing the overheat.
It is far more likely to be the pump than the rack. Whilst randomly replacing things to try and find a problem is not good practice in this case I think it would be the easiest route as there is very little you can do in the way of testing.
First it would be wise to jack the car up and confirm the rack moves with the normal amount of resistance thereby proving that nothing is seized causing the rack internals to work hard. Then pull the drive belt and confirm free movement of the pump.

The pump will be easiest and cheapest to swap either with new or a borrowed unit.

Steve

[Zener]

What Steve said ^ and to add and seeing as its been disturbed I would suspect a collapsed or de-laminated pump supply hose internally or choked reservoir strainer all usually accompanied by a whining from the starving/struggling PAS pump

[halcyongriff500]

Many thanks for the replies. The fluid in the reservoir looks murky, but the pump did not whine even when the PAS packed-up completely. Without PAS the steering was heavy but smooth and manageable, albeit a workout when I parked-up. Access to the rack hoses looks like a real PIA or even the back! I will run it on ramps drain & replace fluid, if no joy, move on to replace hoses and pump if needs be. Trouble is In the current circumstances there is no longer the option of taking it to a TVR friendly garage. Top tip, don't spill coffee on your laptop - mine is now mortally injured! Stay safe, Cheers

[ChimpOnGas]

Zener said:

I would suspect a collapsed or de-laminated pump supply hose internally or choked reservoir strainer

This would be what I'd be investigating too

Reading the OP's description, it definitely sounds like some sort of restriction in the system to me

Also consider if there's a restriction in the return line the pump will be working extra hard too, what's then allowed back into the reservoir may only be vapors.

[Steve_D]

The hoses are very difficult to keep sealed the most common being at the U bend under the pump. If you suspect the hoses at all then replace them with the braided hose kit that is available (can't remember where from just now).

Some TVR garages are still working which is why I'm here in the workshop on a Sunday.

Steve

[ChimpOnGas]

https://chimaerapartsonline.co.uk/product/power-st...

I fitted the above kit some 10 years ago now and it solved all the leaks, which were really just at the 'U' pipe to be honest.

TVR's idea of a bit of bent pipe and Jubilee clips for the connections was appalling, the pipe they used didn't even have flared ends

The kit from Chimaera Parts Online is very expensive for what it is, Pirtek would make you up the same for a fifth of the price, but if you just want a hassle free purchase you may consider paying the premium is worth it, in the end I myself just bought the kit and it fitted perfectly.

[QBee]

Steve_D said:

The hoses are very difficult to keep sealed the most common being at the U bend under the pump. If you suspect the hoses at all then replace them with the braided hose kit that is available (can't remember where from just now).

Some TVR garages are still working which is why I'm here in the workshop on a Sunday.

Steve

I think you mean the one from John Z (Chimaera parts online)

https://chimaerapartsonline.co.uk/

and the kit you want is on the home page.

I had it fitted to my car by the Mat Smith who suggested it, and leaks and problems are a thing of the past.

[ou sont les biscuits]

Further to the last three posts, I had this kit fitted a year or so ago because I couldn't stop a leak from the U shaped hose under the pump, which was pissing oil onto the exhaust manifold.

When I ordered the kit I had a long chat with John Z. He told me that the original spec hoses degraded internally over time, and shed particles into the PAS fluid, which in time would bugger up the rack. So he suggested that not only should I change the hoses sharpish (well he would say that), but that I should flush the system at the same time. So, that was done.

It strikes me that if the OP has murky fluid, then it might be the case that his hoses are past their best, and what he's seeing are hose particles in the fluid.

[QBee]

Word or warning to the OP - John Zubak is a lovely guy, but if you decide to call him set an hour aside.
But then, what TVR person doesn't talk for Europe? Me included, my wife says.

[halcyongriff500]

Hi All, A quick update. SteveD & Zener what you suggested about possible restrictions made sense so I ordered replacement LP hoses from TVR Parts as I had the HP hose replaced about 12 months ago so I figured that should be ok. This was before the upgrade kit was mentioned! To be fair the new hoses arrived within 48 hours and fit fine. SteveD the pas fluid was indeed dark brown so had probably been boiling. A predecessor had replaced the reservoir to pump hose with a silicone hose and that seemed fine if a little squashy no sign of collapse and the internal was clear. The return hose from rack to reservoir had hardened and is suspect. Installing and routing the new return hose was a pain and took ages, probably easier to remove the alternator? All back together, just needs an 'essential journey' to justify the road test. Thanks everyone, stay safe. Graham