Citrojim's AX, Saxo, Pixo, Running and Cycling Tales

Deanxm · Post by **Deanxm** » 01 Nov 2009, 11:08

Hi XantiaV6

But there has to be output seals somewhere, it just means now they are inside the box and difficult to access?

Jim, i know your busy but any chance of a photo of the T/C housing with the T/C removed? the drive for the oil pump looks the same but my box doesnt seem to have this T/C support bush, im just interested in the difference.

I bet your glad the engine came out yesterday

not really the weather for laying under cars today is it

D

CitroJim · Post by **CitroJim** » 01 Nov 2009, 11:48

Hi Dean, yes, delighted we lifted the engine yesterday and not today. Even the ducks have umbrellas up...

The oil seals work on the outer surface of the tubes carrying the driveshaft splines. Easily replaced.
This picture below shows both the TC housing minus TC and one of the driveshaft seals.

If you want any more detailed, I'll do some more as I strip the 'box.

I've been thinking why the bush would have been starved. It must have a lubricant passage from the oil galleries. I'll be soon investigating that one...

Deanxm · Post by **Deanxm** » 01 Nov 2009, 11:56

Thanks for that Jim, all is now clear.
On mine the T/C is open to the Oil pump and there is no way it could starv of oil unless there was none, no bush either, the T/C seems to hang on the flywheel and the splined input shafts,stator mount shaft in the box and the oilpump drive, the 20 really is a totaly different animal altogether.

D

Post by **xantia_v6** » 01 Nov 2009, 15:22

Every automatic tranmission I have seen has a bearing on the oil pump end of the torque converter, it is necessary because the other end of the torque converter is mounted on the flex plate, which err... flexes... so the bearing is needed to make the torque converter run true.

I remember now that that bearing got chewed out on the Borg Warner box of a 3.4 litre Jag my parents owned, shortly followed by failure of the adjacent oil seal and rapid relocation of transmission fluid to the road surface.

BTW, I am fairly sure that on your box, the oil feed to the torque converter will be through the centre shaft, with the return around the outside.

Deanxm · Post by **Deanxm** » 01 Nov 2009, 18:07

Hi XantiaV6

yes your right of course, i thought i was going a bit mad so since it was raining and there is naff all on telly i went back out into the garage, pulled the box out and stripped it again, here is the bearing, you can see it on the oil pump housing/ stator shaft mount.

but the T/C is not held solidly in place, you can rock it to a degree when engaged with the gear box, not sure if this is to allow the T/C to move with the flex plate to which it is fitted, or the reason why the flex plate is fitted (have not got that far with my reading yet)

The thing i dont get is that the oil pump itself seems to have a lot to do with holding the T/C in place, with the T/C engaged with the pump drive gear it does a good job of keeping the T/C in place, fiting the T/C to the box with the oil pump drive gear missing lets the T/C flap about like a sheet in the wind on the inboard end so the bush pictured above doesnt seem to do a great deal,

unfortunatly i run out of time when i stripped it before and didnt get around to fully understanding the boxes operation and moving into my new house this wednesday i doubt if i will for a good while yet either

D

CitroJim · Post by **CitroJim** » 01 Nov 2009, 18:25

That pump assembly, Dean, looks very similar to the 4HP20...

Compare:

(This was a picture taken of my original gearbox strip and is not recent!)

I've been busy today giving the gearbox a good clean up ready for stripping. I'm a great believer in clenliness when doing any job like this and it does help make the whole job more pleasant. An hour of white spirit, scrubbing and blowing dry with the airline sees it all ready for the next phase of work.

Whilst mucky, I also gave the pressure regulator a good scrub and a few other oily bits received similar attention. Then it was a tidy, reorganise and thorough clean of the garage itself. It's now cleaner and tidier than my house

Here's a shot of the gearbox all sparkly clean and ready for opening up...

CitroJim · Post by **CitroJim** » 01 Nov 2009, 18:37

I was lucky today to catch sight of the official ZF repair manual for the 4HP20.

Of great interest was the following statement:

The oil does not have to be changed until it has been in service for ten years.

So, not quite as "sealed for life" as they first claim..

Deanxm · Post by **Deanxm** » 01 Nov 2009, 18:38

That does look very similar Jim yes, yours seems to have a few more pump outlets/inlets though??
anyway, i will stop contaminating the blog now interesting stuff is starting to happen, its looking good 8)

D

CitroJim · Post by **CitroJim** » 01 Nov 2009, 18:59

Deanxm wrote:i will stop contaminating the blog now

No. Don't do that Dean! Keep all contributions coming..

Good luck with your upcoming house move, hope it has a nice, big garage and driveway!

Deanxm · Post by **Deanxm** » 01 Nov 2009, 19:24

Well the flat we rent now has a big drive and garage, the house we are buying has a grass lawn that will be a drive and i will have to settle for as bigger shed as i can get at the bottom of the garden

sadly could not afford a ready done drive and garage..............one day maybe once the bathroom and kitchen.......and heating are done

.

D

Post by **xantia_v6** » 01 Nov 2009, 19:57

CitroJim wrote:I was lucky today to catch sight of the official ZF repair manual for the 4HP20.

Of great interest was the following statement:

The oil does not have to be changed until it has been in service for ten years.
So, not quite as "sealed for life" as they first claim..

It seems a bit odd giving only a time-based lifetime for the oil.

CitroJim · Post by **CitroJim** » 02 Nov 2009, 21:03

After a relatively quiet day yesterday, it was down to business today. Whilst we were reasonably confident the torque converter had failed, it was vital to open up the gearbox and have a check. After a fight with a couple of corroded bolts, those nearest the front of the 'box in direct lime of salt sprays, the 'box came apart.

The good news is that the clutches are absolutely fine after 140,000 miles and on the original oil

Here's a B Clutch (the one that works hard) lining:

The F Brake, which can wear, is also fine. However, looking at the top of the oil filter, the picture is not quite so rosy. The grey stuff is fine metallic powder

The bottom of the 'box contains more of this deposit and a couple of lumps of unidentified metal.

next up for inspection was the oil pump and it was found to be rather worn.

Here's a few shots of it's components showing the scoring. The oil pump gears show signs of fretting and "picking up"

Note the scoring at the green arrowhead and also the condition of 140,000 mile old oil. Not bad at all!

Here's a shot of the pump gears:

Note the damage at the heads of the green arrows.

So what happened? The best we can think is the stator sprag or lockup clutch in the TC began to break up and shed some metal. This found its way into the TC tail bearing and then into the oil pump. The debris visible on the oil filter may be remnants of this or bits of the TC tail bearing. Whatever and wherever it came from, it has wrecked the oil pump and this must be replaced. What we do know is that none of it originated in the gearbox proper

I called for some quotes for spares prices and had a most interesting conversation with the parts man.

I asked for the cost of a new oil pump and torque converter and he said:

"Ahh, I bet you pulled the converter off and found a bearing welded to its neck.."

"Yes, precisely!"

"It's how they all go.."

He went on to say that nobody quite knows why. ZF reckon it's oil contamination and others say it's overheating. In truth the jury is out...

The cost of an oil pump, which is only supplied as a complete unit, is £288 whilst the torque converter is a more reasonable £99 + carriage for a remanufactured item. It is rebuilt by a firm in Glasgow. With consumables on top of that, (filter, seals, transmission cooler) the old wallet is going to take a battering

Thinking on, I wonder if these reports of the odd lock-up and lurch is the first sign of the TC tail bearing going and momentarily seizing?

My own V6 needs a little fettling this week. She's clearly jealous of another V6 in her place and has complained by springing a minor LHM leak from her rear electrovalve

To round off the day today, I briefly saw Gareth in his Activa. he was en-route for the Milton Keynes IKEA and popped in for a quick Lexia session

I really got a quick taste today of what it might be like if I started up my own small specialist business

Deanxm · Post by **Deanxm** » 02 Nov 2009, 21:37

Hi Jim

The cost of an oil pump, which is only supplied as a complete unit, is £288 whilst the torque converter is a more reasonable £99 + carriage for a remanufactured item. It is rebuilt by a firm in Glasgow. With consumables on top of that, (filter, seals, transmission cooler) the old wallet is going to take a battering Twisted Evil

I would like to know who the firm is in glasgow, thats £40 cheaper than i could find a re worked T/C and £40 is £40.
Oil pump price seems very reasonable considering the build of the thing, still a fair whack of money but its not omg volumes of cash.

The condition of the clutches dont surprise me though, have a look at this with a nats wisker under 90k under its belt

D

Post by **xantia_v6** » 02 Nov 2009, 21:55

CitroJim wrote: So what happened? The best we can think is the stator sprag or lockup clutch in the TC began to break up and shed some metal. This found its way into the TC tail bearing and then into the oil pump. The debris visible on the oil filter may be remnants of this or bits of the TC tail bearing. Whatever and wherever it came from, it has wrecked the oil pump and this must be replaced. What we do know is that none of it originated in the gearbox proper

My theory is that the "misfire" I felt driving on the motorway was something breaking up in the torque converter. debris from this would find its way into the bottom of the transmission (but couldn't get through the filter back to the pump) The car drove 45 miles like this. But when the car was stopped for a couple of hours, some oil, with debris, drained back from the torque converter and into the pump. When the engine was subequently started and rum for about 1/4 mile, a peice of debris has scored the pump and then seized the torque converter bearing.

CitroJim wrote: I really got a quick taste today of what it might be like if I started up my own small specialist business

But you did have unusually polite customers

Sid_the_Squid · Post by **Sid_the_Squid** » 03 Nov 2009, 13:10

Interesting how well the clutches have been preserved, and wow is that oil dirty!
Change at 10 years does seem a particularly arbitrary statement, but it lends weight to my suspicion that 'sealed for life' is a marketing ploy as opposed to genuine recommendation from the gearbox designers.