My Kingdom for the ZF4HP auto sump plug thread size !!!

[DrDeath]

Dearest fellow fanatics,

Would someone be so kind as to tell this sorrowful, exhausted, exasperated, googled-out D1 Terrambulator what size thread is on my ZF4HP drain plug pleeeeease ??

1998 D1, 300TDi, 4 Spd auto, some parts seem to be 1999.

It's not the 12mm mentioned elsewhere in these goodly scribes, but the 'fine thread' with a low profile head and a 4mm hex hole with which to manipulate the sneaky little devil.

Seems to be used on (at least some of) the P38 and D2's, but alas, the proletariate over in those unwashed realms shed no light upon my unfortunate and laborious predicament !

The mystery runs thus;
I am in dire wont of installing a temperature sender in the ZF sump, and the drain plug seems the ideal spot. This site is just in front of, and well shielded by, a rather substantial cross member, and the VDO sender sticks out only about 15-20mm. If I can't solve this mystery, I shall use the opportunity to change the filter and gasket and weld a 1/8" spigot in the sump and to hell with the consequences ...


ps. My Kingdom is a little delapidated (due almost entirely to my ownership of this flagship of a once great and proud conveyance), so I wouldn't get my hopes up if I were you. I shall however, be glad to shout the successful informer a membership to one of those interesting Russian sites one finds flitting so subtlety over these esteemed pages.

Yours respectfully,

[AK83]

Sorry can't help with the thread size of the sump plug .. but!

My OEM temp sender switch is playing up. It gets 'stuck' on. That is, the temp warning light on the dash is always on. If I pull the plug and reseat it, it stays off for a while, till it comes back on again .. and drives me bonkers for a while .. till I repeat the process over again.

Sorry for the boring back story, but the point of it is that the location of the OEM sender switch seems an ideal place to locate a secondary temp sender unit for a gauge.
All you'd need is a simple t junction to allow fitment of the OEM(if you still wanted it fitted) and whatever adapter to fit the thread of the sender unit you have.

Location of the OEM temp sender is just under the vehicle very close to the intercooler's bottom hose.
There will/may be a plastic shroud hiding it's location if you look under the car but this comes out relatively easily to ease of access.

Fitting the temp sender at the sump plug exposes it to possible damage from mud/grime/dirt/sticks and stones, even taking into account the large sturdy crossmember as protection, and hence makes it more likely to eventually become an issue.

Even if you're interested in this alternate fitment location, the other unfortunate situation is that I can't help with the thread size of the OEM temp sender unit either!

[DrDeath]

Sorry can't help with the thread size of the sump plug .. but!

Sorry for the boring back story, but the point of it is that the location of the OEM sender switch seems an ideal place to locate a secondary temp sender unit for a gauge. All you'd need is a simple t junction to allow fitment of the OEM(if you still wanted it fitted) and whatever adapter to fit the thread of the sender unit you have.

Location of the OEM temp sender is just under the vehicle very close to the intercooler's bottom hose.
There will/may be a plastic shroud hiding it's location if you look under the car but this comes out relatively easily to ease of access.

Even if you're interested in this alternate fitment location, the other unfortunate situation is that I can't help with the thread size of the OEM temp sender unit either!

Hark and greetings O good Sir AK83 (is that some kind of gun ... but I digress sir ...),

My thanks for your thoughts, time and effort in responding to this most irksome quest.

I admit that I tend to run my kingdom to arguably pedantic lines sometimes, but I've found during a lifetime of metallurgical fiddling, that given half a chance, the Solihull gremlins do run amok if ones' originally tried and proven mechanical thingamebobs are sent the way of the late Heath Robinson (or as the peasants over in the D2 forums might say; if one allows one's doodads to get a bit complicated or tangled).

'Tis for this reason, and after soaking up, nay, verily wallowing in the limitless depths of knowledge and experience (not to mention some most marvellously sardonic wit) bursting forth from these here pages, that I have made the decision to mount said temp sender somewhere on the ZF sump. To whit ...

1) those blessed cooler pipes must run at significantly different temps to the actual body of the ZF itself, so any readings gained along their length are likely to be a tad or two perfidious.
2) not even the Solihull geniii or their serfs or other assorted hangers-on are wont to let on as to which direction the holy oil doth flow within those blessed pipes, which casts a pall of uncertainty as to whether we might end up monitoring oil temps afore or avast yon coolers of oil.
3) our own esteemed Northern Knight of Black didst allude (as far as this unworthy did understand, and please forgive me Sir Knight if I've got it all ballsed up) to the holy oil flowing both fore and yon, depending on gear ranges, direction of vehicular travel, whether you've paid your taxes and the colour of your mankini. That further mires the hoped for accuracy of our oiley task.
4) we Landophiles are supremely fortunate to have that proprietary oiling system that lets us monitor the status of our boxes, shafts and knobs without even looking under the skirts or using nasty expensive gauges etc, but merely to cast a casual eye upon the ground. This same impressive automatic oiling system keeps our undersides clean ... or at least causes us to spend goodly sums of time under our mounts, doodling away with degreaser and rags while we're calculating costs of major rebuilds and how to run it past the chancellor of the exchequer when she's most likely to sign the chit.

So, whilst I am most grateful for your time and efforts Sir AK83, I feel I must stick to my eventual decision to stick my proverbial finger in the dyke itself, rather than some (perhaps only marginally) less reliable pipe away across the badlands of Roverdom.

ps. forgive me for asking a possibly silly question Good Sir AK83, but why don't you replace yon temp switch ? Mine has always worked a treat, although it's required a quick degrease and a tighten of the spades every few years or so. I do find that one has to show the peasants a little attention now and then ...

Again Sir, my humble thanks, and how come no bugga knows the blessed size of the rogue ?

Doc Dee

[workingonit]

Hi DD.

On the floor at the moment, my 1997 zf sump bolt is 12mm (11.8mm), pitch metric 1.5 (in the unlikely event they used an SAE then 16 - not enough thread to help differentiate). No hex in head. I'll leave this here in case some hapless soul really does need the info (ie bolt fell out on the track!). My 1998 Disco has the same.

I wonder if your talking about the bolts closing off ports you can otherwise use for oil pressure readings - they have hex holes. They are in a tight space between the bell housing and the gearbox. I'll see if I can get one out - give the box is on the floor. If this is the info you want, then we'll discuss those free months accommodation in Tamworth later (or to where ever you move)

...OK, I'm back. The bolt closing off the pressure port is 14mm( 13.85mm) with again a 1.5 pitch. You say the bolt you have in mind has a fine thread - have you had one out in the past? Used a 6mm stubby hex fixed to a 3/8th drive. Regular long form 6mm had too much flex.

We have a Dr Death in Darwin, pronounced Deeth...Dr Deeth doesn't quite cut it for roll play

Anyway, that is my bit of Land Rover mechanical fanaticism for the day.

[DrDeath]

Hi DD.

My 1997 zf sump bolt is 12mm x 1.5. No hex in head. My 1998 Disco has the same. I wonder if your talking about the bolts closing off ports you can otherwise use for oil pressure readings - they have hex holes. They are in a tight space between the bell housing and the gearbox. If this is the info you want, then we'll discuss those free months accommodation in Tamworth later (or to where ever you move)

...OK, I'm back. The bolt closing off the pressure port is 14mm X 1.5 pitch. You say the bolt you have in mind has a fine thread - have you had one out in the past?

We have a Dr Death in Darwin, pronounced Deeth...Dr Deeth doesn't quite cut it for roll play

I thankee sincerely also Good Sir/Madam Workingonit, for thy clearly effortful and thoughtfully wrought musings, and for heading 'em this way (and even despite thy uncouth implications of 'roll plays', about which we are not amused), but alas, the screw of interest is still the drain plug on the box's bottom, rather than on her front atwixt the bell housing. It's not the usual 12x1.5mm hex head that everybody talks of, but the finer threaded blighter with the flat, button head and a hex key 'ole. Used on at least some of the P38's and D2's apparently (which makes me wonder now if the old girl's received a transplant at some stage in her previous life, although my native (Royal) cunning and exquisitely honed observational skills reveal no evidence of same). I shudder at the thought of wading into the unclean depths of the D2 forums however, when I've only just learnt to annoy and offend everyone over here in the D1 arena ...

Now, for the news:
There has, since my initial and already extensive research and publication of my quandary (which remains sorely unsolved ... he says ... rather pointedly ... ladies and gentlemen ... just saying like ...), emerged a rather infamously annoying small winged insect within the medicinal lotion ...

In the process of further, now increasingly despondent and unproductive investigations, I chanced to stumble across a reference by one of our Landroverie compatriots to an apparently decent purveyor of all things automatic transmissiony ... vis: <automatictransmission.com.au>
These seemingly skilful and experienced chaps and/or chappettes put it thusly (and I quote):
Knowing where to put the temperature sensor so that it picks up on the hottest temperature point is the most important factor ... Most transmissions have two cooler lines that allow the fluid to flow through the oil coolers. One will be a ‘Hot’ line with the other being the ‘Cold’ line. The ‘Hot’ line has oil flowing from the transmission at it’s hottest point and this is what we want. Using the ‘Cold’ line is going to give you false readings as this is oil that has been cooled already. We have seen the occasional gauge with the sensor drilled and fitted to the transmission pan. This is quite frankly pointless as you are getting a delayed temperature due to the cooled oil mixing with previously cooled oil. (end quote).


Well Sirs and Sirettes,
Don't I feel a nit (though an increasingly educated and microscopically less incompetent nit) ... and not just a teeny bit terrified that I may have misunderstood the Sable-hued Knight of the North, thereby risking any chance I may have had of snatching the Landrovery pebble from his hand during this lifetime.

To business then:
1) Squire AK83's suggestion of using the existing oil temp switch's location is shared by many others, and the presence of the OEM switch at that spot almost convinces me that the magical black liquid must travel in only one direction past that point. This would be an ideal solution if only I could absolutely confirm that (a) the temps at that spot are not significantly different to any temps found closer to the box and (b) that the holy leftovers of prehistoric sea life flow only one blasted way through that port (ie, from the box to the cooler), rather than changing direction according to some arcane lore of Solihull wizardry.
2) Squire Workingonit's energetic investigations make me wonder if we can't bung an oil temp sender in one of the pressure ports in the front of the box ? I even have a 14x1.5mm X 1/8"NPTF adaptor to fit the thread sizes Mr/Ms Workingonit has discovered. Although 150psi or about 10atm at those ports is rather impressive, my fears are allayed when I realize that the pressure will be the same at the OEM pressure switch port, and that that fine instrument seems to cope reasonably well (at least for a few years away from the showroom floor).


Now, lest someone accuse me of unnecessary verbosity or garrulousness, to action:
1) can any kind soul confirm or deny that the oil travels only one way from box to pressure switch, to cooler/s and back to the box ?
2) can anyone think of a reason why we can't stick a temp sender in a pressure port on the front of the ZF box (supposing I discover that it will actually physically fit) ?


Many thanks in anticipation of any info kind people.



ps. regarding the moniker Mr/Ms Workingonit, I did write a spiel for the 'about me' thingy, but it disappeared unto the ether before I was able to tether it to the spot. In short, I'm the proud owner of a rare genetic mutation whereby I'm allergic to sunlight. My first proper vehicle was a Series 2 shorty, whose already very limited glassy bits I reduced and covered over and shielded and blacked out as much as possible ... much like that combi in the famous Count Yorga scene of the 70's ... so, combined with my natural interest in physiology and medicine etc, you can probably see why my mates gave me the nickname ... now, I don't know how all this forummy stuff works, but I suspect someone out there is at this very moment considering moving or removing these fine literary efforts to another place and time ... so it's goodnight from me and its goodnight from him ...

[AK83]

Maybe I'm a bit naive to assume that Landrover engineers would have a good reason to place the temp sender switch where they have .. and it's a well known fact that I'm a bit naive.
(actually retract that, I'm not so much naive .. so much as ignorantly optimistic! )

and ..

if your magical, industrially cleansed, prehistoric sea life remains, are flowing black .. I reckon you need to do a lot more than to keep an eye on it's thermal properties

[workingonit]

I think Knight of the North has decided to set in the West...

Good luck with the temp sender - photos will do

[DrDeath]

Maybe I'm a bit naive to assume that Landrover engineers would have a good reason to place the temp sender switch where they have ... :D and .. if your magical, industrially cleansed, prehistoric sea life remains, are flowing black .. I reckon you need to do a lot more than to keep an eye on it's thermal properties :p

I think Knight of the North has decided to set in the West...

Good luck with the temp sender - photos will do [smilebigeye]

By Jiminy, you two coves are quick to poke holes in a man's dissertations ... it did occur to me that ATF ain't exactly black, but I didn't think any sod would notice ... and I realized too late in the wee hours of last night's continuing mind numbing sump screw research that Sir Black indeed seems to have scarpered off west.

However, given that you've both been kind enough to lend a hand in this most exasperating mystery of the tranny's screw, and given further that I've now solved the wretched puzzle, I shall vouchsafe thee both a little leeway in my magnanimity, and stay the guillotine ... for the moment you understand ...

Now, where was I ... oh yes ...

EUREKA !!! The snotty little toad of a ZF sump plug thread is an M11 x 1.0 !!!!!

... that was a bit of a let down really ... in light of the fact that I'm not going to use the blasted thing after all this ...

Fossicking round under the old girl's skirts this evening, it became apparent that the OEM sender site is indeed so remote from the box, that there must be an appreciable heat loss by the time the magic RED stuff goes past that point. It's a steel pipe, and pretty long, and exposed to lots of wind, heat, cold, etc. I further suspect that the OEM oil temp switch is about as accurate as the coolant temp gauge - very helpful if you just want to know when you've cooked your box.

The rather assertive words of the tranny experts quoted earlier suggest that the sump is also a bit useless.

So, the best mounting site seems to be on the box itself.

Thus, to plan C: to source possible sites for a temp sender on the transmission itself.


Oh, and in case you were wondering good sirs/sirettes (you're still not going to tell us are you), how I finally fulfilled my Quest Of The Tranny Screw, it was eventually resolved by the simple method of spending $200 odd hard earned on a filter kit and lovely new RED oil (... Mr/Mrs AK83 ...), then following the factory workshop instructions, I duly jacked up the aerial, removed the tailgate, took off the rear diff, popped the windscreen, bought another car, drained the oil and voila !!! The horrid little relic was in my hands at last ...

[bee utey]

The oil temp in the pipe pre cooler will be a much more relevant temp reading than you think. The oil has just left the torque converter in high dudgeon where it's just had it's ass thrashed, then returned to the sump after being cooled down a wee bit. Clamping a sensor via a split brass block to the hot pipe nearer the trans might possibly give you a similar reading.

[workingonit]

Hoping your 'filter kit' included the one residing inside the sump (bolted to the valve system). Nice to start everything off fresh.