HAVE 740GL 1990. My automatic transmission ZF4HP22 has 160,000 miles. Mechanic just told me they usually don't last that long; life span is usually around 140,000. He said that while most Volvo transmission last, this particular one doesn't.

Is this true? And what is the most reported mileage from the ZF4HP22?
He said to replace it would cost over $2,700. So far it's running ok; no problems so far. But I would like to know if I should be expecting some trouble soon.

Any help on this issue would be helpful. THANKS

I'm in malaysia and I have two ZFs in the family. Mine's an 89 740 whereas the other is a 94 940. The US would never had a ZF 940. We don't have the smog test here so I presume that's why volvo still had ZF in their cars here up to 94.

Both cars has bout 300 000 km which is young compared to 250k miles one poster mentioned. I found it interesting what Chris said not do a full flush. I did a full flush on mine twice. First with regular ATF, 2nd with synthetic. No problems whatsoever except the 2nd flush did made the hard shifting slightly smoother.

Aslan
Malaysia

Our full flushes were on cars that the transmission fluid was OH MY GOD FILTHY. Because Volvo doesn't say, in bold writing, to change the fluid every 20K, no one did. In fact no one ever changed their fluid, ever! Many people used to believe, and some still do, that the car must be serviced at the dealer until the warranty is up. Well, this is two tranny fluid changes later, in most cases...and of course two tranny fluid changes not done. My Dad always said, "there's a box of Tide, in a quart of transmission fluid," and yes, transmission fluid has a high detergent content. It seems once the tranny fluid is dirty, the interior of the transmission doesn't appreciate being oh-so-cleaned...so we have decided to be better safe than sorry...when we "ate" those two transmissions are business was "new", so it's a painful memory.

So hopefully, I've explained by theory...

Chris

Very well explained. That reminds me not to do a full flush on the 940 ZF as the fluid is dirty and has never been changed for donkey years (car is not mine). Thanks for the reply.

Aslan

I had 250,000 mile on my '86 745 GLE. Landrover uses the exact same tranny, just bigger, and the techs I know haven't replaced a single one.

IIRC, Volvo stopped using the ZF tranny after the 1988 model year. The tranny should be an AW70L.

If the shifter is PRND21 and has a button on the side, it's an AW. If it's PRND321 and no button, it's a ZF ... and the only plausible reason is that someone else swapped one in.

-- Kane
--
Blossom II -'91 745Ti/M46 ... Bubbles -'74 144GL/BW35 ... Buttercup -'86 245GL/AW70
The Wayback Machine -'64 P220/M40 ... The ParaBox -'90 745GL/AW70

I'm not a fan of the ZF, but as a trans man, I can tell you that it's not a bad transmission.

The problem already mentioned is with reving when not in gear.
The cause is that there is no bleed down valve in the direct drive fluid circuit. When it builds pressure, it retains it. In the eyes of the engineers, this was a good thing. In reality, not so. There is no lubrication problem with this trans, just the opposite, the lube / pressure doesn't dissapate well. The drum remains partially enguaged and will burn the friction discs and stators when prolonged high revs in P or N are experienced.

Properly cared for, this trans will last just as long as any AW (though I definately preffer the AW's). If you're somewhere that requires smog testing (also a good idea to have this for any mechanics that might work on your car), drop by your dealer and get a copy of the service bulliten and smog test advisory. Most will still have copies to hand out, if not, they're easily found online. OR I could send you one next weekend if you can't get it otherwise.

ALWAYS remind a mechanic not to rev the car in P or N without first doing as the papers direct and for no longer a period than listed. Also make a couple copies, chances are that it wont survive your mechanic's shop.

If it ever starts acting like it can't decide wether to stay in propper gear or downshift for no apperent reason, it's already been abused in P or N. Caught early enough, the D/d piston gaskets can be replaced b4 burnouts occur. 99% of these transmissions that have died will have parts of piston seals in the pan.

As already stated, should it die on you, the AW swap is an easy one and in most cases cheaper.
At this point though, don't worry. Just get the papers mentioned and read up.

Hi

From your experience as a trans man, what could cause a hard shift into 2nd and 3rd both up and downshifting, in a ZF. Mine's been doing this for years now and till now I can't get a definite answer as to what's the problem. Does it have a valve like the AW? Not many people are familiar with the inners of the ZF. Hope you have an answer. Thanks

Aslan

a few things actually, but here's some ideas (by the way, I've yet to work on too many ZFs as most would rather have them swapped, and I've never had this issue with any of my own)

Does it seem to bog the engine excessively when first put into gear? If so, suspect TQ stall incorrect (very rare, but happens and normally not an issue to be very concerned with on the average car)

2) line pressure excessive. The first thing to check here is the detent mechanism.
Simply remove the detent connection from the throttle link on the throttle body. No need for tools, just turn the throttle 'wheel' by hand until you have enough slack to remove the cable lug. Drive the car lazily and see if it shifts any harder. If softer, adjust detent. If no change, tighten the cable 2 full turns of the nut (13mm if memory serves correctly on most). If shifts worsten, loosen the detent back to original tension and 2 more turns in reverse. In either case, if it drastically changes the shift feel or if it improves it, adjust the detent.

3) gunk blocking up the reg. A good thorough flush is the best cure here.

4) seperator plate badly worn and check ball sticking. Only true fix is to drop the lower valve body and seperator plate, then replace the sep plate and all check balls. (not difficult if you've done it b4, if not, needs done by a pro)

5) gov sticking. best fix is to remove and replace the gov.

All are kinda vague, I know. Sorry. If I had the car in hand, chances are it would be an easy diagnosis.

There is another easy option, but I'd have to study the ZF's fluid flow schematics to say if it would come into play here. On the early GM 700R4 tansmissions, a kinked cooler line would almost always cause an excessive hard shift (most ppl didn't notice as the trans was a stiff shifter to start with).

Do you have this bulletin and smog-test advisory in file-format (pdf, doc etc) ? If so could you email it to me please ?

I'm assuming this applies to non-dynamometer type smog-tests, where the car is revved in Neutral / Park. Dynamomenter-based tests where the revving is done in Drive would not carry any risk. If this assumption is wrong, please let me know.

Thanks !

All I can find right off are the BMW docs. Sorry. I'll keep looking, I have them saved somewhere.

Never do a full fluid flush; let some out, put some new in, let some out, put some new in. We use Valvoline Max Life, and a BG product that is a transmission conditioner. The BG products do work, but the tranny conditioner smells suspiciously of 90wt. Made the mistake of a full flush twice; first time, the car lost reverse, we think, "that's odd", for free we replace transmission; second time, the car ONLY had reverse; we think, "oh, there's a pattern here", for free we replace transmission. Since we have only done partial fluid changes, I have had quite a few customers exceed 200K, and about 3 customers exceed 300K. Here in the States the last year I've seen a ZF in is a 1988 740. $2700.00 seems a bit steep. We change them over to AW70/71 when they go, so we have to swap the shifter, the cross member, the driveshaft, the tranny (obviously) and run the wiring for the overdrive. The cost is about $1600-$1800 depending on whether I have to buy the parts, or if I have a donor car.

Hope this helps,

Chris

They suffer from a peculiar problem that causes complete self-destruction if they are revved in neutral or park, such as when doing an emissions test or while stopped. When in N or P, idle speed only. It's caused by poor lubrication.
Make yours last much longer by flushing the fluid and replacing with synthetic gearbox oil. Mobil 1 Synthetic ATF is my favorite, but Castrol and others make similar products. Miracle stuff: reduces wear, improves cooling, makes trannies last forever.

Hello,
As far as I can glean from this board is they can die if you rev them up in neutral and not in gear. Eg while having your car tested for smog. I havent got an automatic in the UK so someone on the forum will tell you their mileages. Regards KYLE123.