Zf 6hp26 transmisson oil mix with water

[Hede267]

Hi there im new to this but just wanted to discuss a problem ive had with my ford falcon fg 2009 with a auto zf6hp26 transmisson, so its my partners car and shes been driving it for a couples weeks noticing it making a werid rubbing sound now and then around 50-60km/h and now it got worse by it surging when in second gear in between 1-2 revs would rise and go down quickly , I took it to a transmisson specialist and he told me theres a 5% percent chance it could just need a service or its pretty much had it but he was pretty certain on it being done , now I myself like to work on my own cars other then paying thousands of dollars so I was going to do a whole transmisson swap so I got a hold of a second hand one in good condition and low kms for cheap . My friend told me to check the level of the transmisson oil so I took the filler plug out and very milky oil started bursting out . Firstly im thinking how is there water mixing with it and it shouldnt be so full so I let most of drain out till its at level with filler plug . I check my radiator water just to make sure and then theres milky substance in there aswel . It should be super clean cause I only just done a flush and fill on the radiator a couple months beforehand. I look online to find out where the water and oil are close together and I find out its the only part I know to my knowledge is the heat exchanger,  so I go ahead and replace that with a second hand one I got with the trans and with the old one I try pressure the hose through the radiator input on the heat exchanger and block the output one to seen if water comes out of the oil lines . No water came out of the oil line so im guessing it must only happen when its under heaps of pressure and very hot if its not that then there must be another meeting point were the trans oil and water meet ? But any way I got rid of the milky water out of the radiator and topped it up with coolant and left the milky oil in the trans and took it for a drive it drove way better and stopped surging so I might try doing a drain and refill on the trans till it runs clear then service . But im only hoping it works . Sorry about the big story but itl be better if I said everything , if any one can help or give me tips on this il be greatly thankful as I dont much but trying and trying to do this on a low budget

[k31th]

You did it the right way in attacking the stock ZF heat-exchanger, as that's the only point where the transmission oil and the coolant meet each other very closely. The metal that transfers the heat between the transmission oil and the coolant is quite thin and is susceptible to corrosion, especially if the coolant is not "clean" or not maintained often. Even the ethyl-glycol slowly wears through the metal over time, even with perfect maintenance of coolant. The only way to be sure that this issue is avoided is to replace the heat-exchanger with a transmission oil cooler that uses a radiator instead. A way to be "safer" is to replace the heat-exchanger periodically as an "insurance" policy (as the stock heat-exchanger is considerably cheaper than a ZF replacement, many many times over)

 

The fact that your ZF has coolant in it and your coolant had transmission oil in it is usually the lights-out for the clutches, tight metal contacts etc in your gearbox. But if it only briefly happened, flushing both the coolant and the transmission fluid until all milkiness is removed may have saved your gearbox and engine coolant galleries.

[Hede267]

Thanks for the comment keith , im definitely going to look into getting a transmission oil cooler . Im still gonna try flush and refill the trans oil till its clear just to see how the transmission is . Il definitely be doing the swap though thanks again keith !

[El Andrew]

Grab some Gulf Western fluid to do that - much cheaper than Lifeguard, especially when you don't know whether the box will live or not. About $150 delivered direct from GW.

[Hede267]

Sweet mate will do

[Puffwagon]

http://www.furitech.com.au/index.php/zf6hp26-transmission-introduction/

 

Don't put new fluid etc into a water damaged trans.

 

Get a second hand trans that isn't stuffed, get a new radiator and a new heat exchanger. Clean and dry the oil lines to the heat exchanger then change the filter and fluid etc.

 

If you do it yourself you should be able to get it done for under $1500 all up.

 

You won't be fixing a water damaged zf transmission with a flush. Even if you stripped it and cleaned it there could already be enough damage to warrant binning or rebuilding it.

 

Just my 2c.

[Puffwagon]

Another link from the same site if no one found it.

 

http://www.furitech.com.au/index.php/category/zf-friedrichshafen-ag/6hp26/

[k31th]

that's a great link well done, Nath!

[Puffwagon]

Just trying to help is all. The more we share, the better off we are.

[Hede267]

Cheers for that puffwagon definitely doing the trans swap this weekend after reading that story cheets ?