Siezed Transmission Filler & Drain Bolts

[teeerex]

Hi - I am just doing some prep work for changing the transmission oil on my MY99 C4, I have the Oil, I have a pressure pump to pump it in but I can't undo either of the filler/drain bolts on the rear transmission ...

btw Loren - on my car they are 10mm Allen for both, not 17mm (that is very large - are you sure that's correct, that's bigger than the bolt itself (!).

Anyway, I've sprayed with penetrating oil and will leave overnight to see if that helps. Transmission is 'warm' - plan was to loosen the bolts and then go out for a run to get it nice and hot before draining. Car has done 55K so assume they haven't been cracked opened in a while ...

Has anyone got any ideas on how to loosen them - 3/8" socket bar is physically bending with the pressure I'm putting on it - don't really want to snap the allen in the bolt ... <_<

Perhaps try it when it's cold, or perhaps very hot ?

PS - Haven't even looked at the front diff yet ...

Thanks!

Richard - UK.

[Loren]

Some of the plug types/sizes vary depending on the year of the car (I mentioned that in the DIY). The best tool is likely an allen socket with a breaker bar.

The plugs are only supposed to be torqued to 22 ft/lbs. (30 Nm). Perhaps Tommy Torque checked them last at an OPC? :lol:

Are you sure you are turning counterclockwise?

[teeerex]

Loren - ok thanks for the reply. Perhaps the new models use a large Allen size so they can undo them without snapping the 10mm allen socket like I probably will tomorrow !

How about a hot transmission and I freeze the bolt (with freezer spray) and then try the pen oil for a few more hours ... it may crack the chemical bold enough for pen oil to get in there ...

Tried to tighten the bolts too - as I know this sometimes breaks the bond enough to then undo it again...

Why couldn't they just use a normal hex headed bolt ?!

Richard.

[Mother]

Loren - ok thanks for the reply. Perhaps the new models use a large Allen size so they can undo them without snapping the 10mm allen socket like I probably will tomorrow !

How about a hot transmission and I freeze the bolt (with freezer spray) and then try the pen oil for a few more hours ... it may crack the chemical bold enough for pen oil to get in there ...

Tried to tighten the bolts too - as I know this sometimes breaks the bond enough to then undo it again...

Why couldn't they just use a normal hex headed bolt ?!

Richard.

I used a standard L type allen with a qwick shock on it with a hammer and it finally broke loose. Remember righty tighty lefty loosy! Easy to forget when under car.

[McCullough]

... I have a pressure pump to pump it in...

What kiind of pump are you using for this? Where did you get it?

--- Tom

[teeerex]

... I have a pressure pump to pump it in...

What kiind of pump are you using for this? Where did you get it?

--- Tom

Hi - I'm just using a 'bug spray' pressure bottle, removing the spray head and fitted a short length of polytube. bottle and then filling it with Transmission oil instead ! I've warmed the oil first to make it as liquid as possible and it pumps it fine. I've even got fingertip control via the switch on the sprayer !

I also plan to use this for a pressure brake fluid bleeder once it's all cleaned up ! I'll post again once I've suceeded in this .. (similiar to the 'Motive' bleeder - but at about 1/5 of the cost ...)

Success in getting the caps out btw - use a 1/2" Drive 10mm allen socket and a 2 ft breaker bar and it snapped open after a significant amount of pressure - that was no low torque setting ! 3/8" socket would have snapped I think.

Only partial success though as the front diff is 17mm Hex Bolts - I can get to the drain one easily, but the filler one is a pig - I've rounded the head as I can't get any pressume onto the socket to keep it in place - even with a extension bar. I may have to remove the near side front wheel and use a very long extension bar ...

[teeerex]

..just to complete the topic - these pic's may be useful to someone in the future - use to supplement Loren's DIY ...

1. Make sure the transmission is hot / engine is hot - a good freeway thrash should do it ..

2. Jack up the rear AND the front of the car - it is important the car is LEVEL otherwise the oil level will, one not all flow out and two, be the incorrect amount when you refill it.

3. Start with the FILLING plug - if you can't shift this, then at least you can take the car to the OPC and let them do it !

4. On MY99 C4 the filler/plug is a 11mm Allen type plug so I used an 11mm 1/2" Drive Socket + sufficient leverage (in my car a 2ft breaker bar ..)

5. Remember to have a tray to catch the oil ...

6. It will gush out once the plug is removed so don't get scalded ...

7. Plugs :-

8. Filler hole :-

9. Drain hole :-

10. Leave it to drain for 15-20 minutes ..

11. Refit the drain plug - to 30Nm :-

12. I used a 'bug spray' system to pump in the new oil. To do this effectively the oil really needs to be warmed up or the pump rate is very slow. I simply filled the pressure bottle up with 3L of oil and left it in the airing cupboard for a few hours..

13. Using maximum pressure (about 3bar) I simply put an extra piece of tubing on the end of the spray arm and pressed the trigger - not a single drop split...

14. When you get near to full, slow down a bit and watch for when it comes back out the filling hole. Tip here is to use the gauge on the side of the pressure bottle to give you some indication ...

15. Put back the filler plug - again to 30Nm :-

16. Clean up the overflowing oil and plugs etc

17. You're done !

I've omitted the front diff (C4's only..) as once I find a reasonable way to get off the filler bolt, I'll update this post ...

Cheers,

Richard.

[teeerex]

As promised - I'm updating the post as I managed to loosen the front diff filler bolt in the end ...

I raised the car higher than I did for the rear transmission to give myself some leverage on the breaker bar. My MY99 used one 17mm filler bolt and another 17mm drain bolt (with magnet inside) - I managed to damage the filler bolt last time around with a multipoint socket but managed to get a impact socket (hex only) socket on there nice and tight.

Remove the front underbody plastic shroud - 4 nuts, 6 'clips' (mind your eyes taking these out!)

The secret is to remove one of the cross members (see below - 16mm Bolts) and use a 15cm approx extension bar on the socket to give you clearance into the gap you just created.

I then used exactly the same method as the rear - drain off the old oil, replace drain bolt and pump in the new using my modified bug sprayer - I warmed the oil more this time (almost 'hot') and it flowed very quickly into the filler hole.

This pic shows the filler hole with the now removed cross member. The cross member 16mm bolts were in the region of 100-120 Nm to undo so I did them up to a similiar torque ... :-)

Put back plastic shroud, remember to slot into middle shroud and line up with clip slots before you tighten the nuts. (don't overtighten, they are only plastic..)

I hope this helps somebody out with a C4...

Cheers,

Richard.

[munro86]

Excellent Richard, very well covered. Just a question, what is the brand of that nice looking torque wrench?

Thanks again

Jason

As promised - I'm updating the post as I managed to loosen the front diff filler bolt in the end ...

I raised the car higher than I did for the rear transmission to give myself some leverage on the breaker bar. My MY99 used one 17mm filler bolt and another 17mm drain bolt (with magnet inside) - I managed to damage the filler bolt last time around with a multipoint socket but managed to get a impact socket (hex only) socket on there nice and tight.

Remove the front underbody plastic shroud - 4 nuts, 6 'clips' (mind your eyes taking these out!)

The secret is to remove one of the cross members (see below - 16mm Bolts) and use a 15cm approx extension bar on the socket to give you clearance into the gap you just created.

I then used exactly the same method as the rear - drain off the old oil, replace drain bolt and pump in the new using my modified bug sprayer - I warmed the oil more this time (almost 'hot') and it flowed very quickly into the filler hole.

This pic shows the filler hole with the now removed cross member. The cross member 16mm bolts were in the region of 100-120 Nm to undo so I did them up to a similiar torque ... :-)

Put back plastic shroud, remember to slot into middle shroud and line up with clip slots before you tighten the nuts. (don't overtighten, they are only plastic..)

I hope this helps somebody out with a C4...

Cheers,

Richard.