I have a some jobs (coolant, oil) due on my S4 which needed me to take the belly pans off today for first time (interesting to see which screws previous owners/mechanics had lost, the odd sizes some had been replaced with - one was a 1/2 inch imperial head -, and to find various bolts, hose clips etc I'd dropped in the past!).

This isn't one of those "can I leave the pans off in future" posts. getting up close and personal with pulleys and alternator so low off the ground makes me glad the pans are there.

While I was underneath I made sure to check the position of the block drain plugs as coolant change is due. I know you can do this procedure by removing hoses and thermostat and various flush/drain procedures, but I'm thinking that it's more straightforward just to drain the block via the plugs as well as the rad plug.

I know there's a risk of stripping these plug holes so I just wanted to check how likely it is that I won't have a problem with carefully trying to remove the block drain plugs. People usually post when there's a problem so have any of you had a smooth experience with coolant drain the 'orthodox' way, or is the advice to avoid removing the drain plugs? Visually they look OK. Have given them a first spray of penetrant oil. Any other precautions to take when attempting to loosen them or should I just banish the thought?

At least it gave me a chance to give both pans a good clean. I was surprised at what good condition they were in considering how low the car rides.

Thanks in advance.

 

Just use a combo or flare wrench that fits tightly and carefully apply torque. A long double-combo offset wrench works well for me -- it takes a bit of force to break them free, don't tighten it with the same amount of force that it took to break them free! 26-29 ft-lbs is the spec you should tighten to. You should replace the sealing washers too.

 

Thanks Dave - I have new sealing washers ready and will check whether one of my flare wrenches fits.

 

I've pulled the block drain plugs many times. I don't think they're especially prone to stripping, at least not more so than any other bolt. Just my experience.

 

IMHO the offset double-combo wrench is preferred because it is a longer wrench, giving you more control at a given torque, and the offset helps clear obstacles that may be in the way as you swing the wrench. A socket would be fine too -- key thing is you need good engagement with the plug and you need leverage.

 

I've used a standard ratchet to remove them.

The loud 'craaack' sound they make when they break free gives the old ticker a boost!

As others have said, reinstall with new crush washers and I also recommend applying some anti-seize compound to the threads prior to re-installation.

 

And do not forget to wear your swimming trunks - my most hated job on the 928.

 

I've had no trouble with those plugs despite their reputation.

 

Thanks for all the advice guys - I will go in there with ratchet, swimming trunks <LOL> and optimism!

 

A socket/ratchet is the ideal solution, ring spanner doesn't quite give the leverage needed, and an open spanner garantees rounding the plugs.

The problem is the air injection plumbing (perhaps this only affects RHD cars) because this makes access on the drivers side very difficult.

Although it's a little messy, it hardly warrants Roger's most hated job tag!

If you fail to get the plugs out (I couldn't even find them the first time I tried) then Wally has written an excellent writeup on the fill flush method.

 

Roger psoted
Well said, the drain plugs came out OK but last time I managed to get water over my inspection light; simultaneously got a shock and blew the lamp.

I have tried plugging various types of tubes into teh holes but still get coolant everywhere - tastes quite sweet but highly poisonous

Marton

 

DO not use flare wrenches.....use a box end or socket only.

Cheap, even some good flare wrenches strip bolts faster than a piston hits the valve on a S4 belt failure at 6000 rpm.

Strip that bolt and you are in a world of hurt...

 

Hmm well I'm pretty sure I'm looking at the right bolts (I'll post pics next time I get underneath) on very similar model to yours Paul (88 S4 Auto) and it looked like a clear shot at the bolt on the driver's side, but a pipe possibly getting in the way (depending on thickness of ratchet head and socket) and/or how long to le on the passenger side.

Wally's write-up makes me nervous because it talks about getting the engine up to temp before flushing/draining/refilling but I worry about putting cold water in when the block's hot and/or how long to leave it to cool before adding cold. That's why I hope to do a straight drain of cold coolant via the drains.

 

WSM says 33-36 ft-lbs for the block plugs - just did this last weekend. Rad drain plug is 13-17 ft-lbs.

Roger is right - trying to avoid and then contain the escaping coolant is probably the roughest part.

 

about
I heard about doing this when you change the oil but it is new to me to do it when changing coolant - strange idea

Marton