Checking for rotboxes - rust, corrosion & FILLER JOBS!

[Outrun944]

Hi guys

Sorry if this question has been asked before, and I've checked Clarks Garage buying guide (http://www.clarks-garage.com/purchase.htm) and the topic here (http://www.porscheclubgbforum.com/tm.asp?m=38842) but I've not really found the answer and help I'm looking for.

Basically I need a bit of a noobies guide for inspecting a car for corrosion underneath and filler jobs (some of you will remember my 'Disaster!!' topic) and I don't want to get stung again. I'm off to view a car to buy tomorrow so could do with some quick assistance.

I'm not able to get a qualified mechanic out with me and RAC won't do vehicle inspections for cars over 10 years old ... so it'll be me and a torch jacking the car up a bit to try and see!

Can you give me some advice and guides for finding filler jobs? Someone a dunce like me can follow and know when I find one
I'm confident in checking out other possible problems with these cars now, it's just this horrible issue and don't want the same disaster again

Many thanks in advance!

 

[barks944]

Someone should do a technical article on this . We could pull together all out rust pics and stick em in a thread!

 

[Outrun944]

ORIGINAL: barks944

Someone should do a technical article on this . We could pull together all out rust pics and stick em in a thread!

Actually, some underneath photos and shots of a good 944 Lux without any filler jobs would be really useful so I can compare to the photos I have of my rotbox!


I see that you can take off the vents on the door sides and poke a torch in ... you can see a small amount of the sills yea?

 

[zcacogp]

ORIGINAL: Outrun944
I see that you can take off the vents on the door sides and poke a torch in ... you can see a small amount of the sills yea?

Yes, that;s a good place to look.

And all along the cills, from front to back, from underneath. On some models there is a plastic trim piece that runs from front to back, and you'll need to look around/behind this as best you can.

And (on turbos and S2's) the bottom of the front wings. Common rot place this.

And around the rear wheelarches - all around them, at the top as well as at the bottoms.

And around the rear numberplate and lights.

And check around the windscreen for rust there, from a badly-fitted screen.


Oli.

 

[Outrun944]

Cheers Oli.

I guess its fairly easy to spot if sills are rusting.

But what if it's been covered with filler?


OK here's some example pics of my rot box -

If I run my hand along the inside there's this horrible black stuff that I can scrape away ... I guess that's the filler right?

What should it look like and where can I find the join with the floor pan? What/where exactly is the inner and outer sill?
Sorry for the dumb questions


btw ... I'm looking at 1984/5 944's .... the ones with the square dash (cause I love them!) and power steering as standard.

 

[pauljmcnulty]

I see that you can take off the vents on the door sides and poke a torch in ... you can see a small amount of the sills yea?

This is all you need to do to inspect the sills.

Any 25-year-old car will have a bit of corrosion, a 944 less than most, so check the usual areas like wheelarches, windscreen surround, all bodywork seams, around lights etc. Anything more than light bubbling is an indication of a car that's not been well looked after.

The sills, however, are more of a problem, together with the area in front of the rear wheels. This is where the seatbelts mount, and the rear suspension, so it's MOT failure at best.

When the black vent is popped out, the hole is big enough to get a camera (or phone) into. It's easy to see the rear corner of the sills, directly below the vent, which is where the problems will be evident. What you want is a load of sticky yellow stuff, showing it's been waxoyled, and no more than a small amount of surface rust. Bad corrosion, or even daylight, means new sills, reapirs to inner sills, and a bill for up to £1000 per side, depending on how permanent a repair you want. You can get a picture of the whole sill length from the vent, just don't drop the camera. []

This is a pic of a sill that needs attention, but isn't anywhere near MOT failure yet (and wasn't a year later). This is about the limit of what I'd call "normal", a car that's going to be worth repairing without going mad on costs, as long as it's priced accordingly.

 

[FistsOfHam]

Running along the bottom of the sill it shouldn't be smooth like the one in your picture. Mine has various drainage holes running along the entire length of the sill. If I remember I'll grab a pic of mine tomorrow whilst I'm underneath it.

 

[barks944]

The horrible black stuff is probably waxoyl. Its a wax based rustproofing.

 

[zcacogp]

ORIGINAL: barks944

The horrible black stuff is probably waxoyl. Its a wax based rustproofing.

... which would mean it's a good thing (someone has cared for the car enough to apply it), but a bad thing if it has blocked up the drainage holes.


Oli.

 

[morris944s2john]

Yes, black sticky stuff is rust proofer. Filler is white and hard and forms dust when you rub it with sandpaper.

The car does not look bad at all from those pics. Maybe we need to see some close ups of the sills.

 

[Outrun944]

Thanks everyone for the advice so far, especially Paul for taking a pic for me! (ps - Paul... did you get my PM I sent you?)


I viewed the car, but left unsure and going back later this week.

I inspected the sills from the inside opening the vents on the door pillar - looks really good! Much less rust than in Pauls pic, and also pulled up the carpet in the boot and looked at the rear arches and looks fine!

But, there's tons of that black gunk underneath, like my current rotbox 944 (as per pics) - which I presume is the waxoyl.
Just leaves me frightened its covering something up beyond the sills.

My rotbox has a report saying its rotten where the rear suspension is for example, along with jacking points ... how I can check/test for this?
I presume the jacking points are the 'square' shaped metal box that protrudes out ... the edges of this on the car I looked at are a bit rusty and worn. How can I know they're not going to crumble under pressure like what happened to my current 944 when it was put on the lift?

Cheers!!!!

 

[Outrun944]

Also, just wondering ... is there anyone around the Hertfordshire area or anyone you know that would be kind enough to come out with me and quickly inspect the car?

 

[vince944red]

Black stuff - can hide a lot as well as protect
White stuff is usually filler
Waxoyl is a brown colour and obviously waxy - you can't confuse it with black stuff.

Nobody has mentioned the best filler detector - a magnet, obviously a magnet does not stick to filler and if no force at all is felt on the magnet then there is no metal there at all either.

 

[Outrun944]

ORIGINAL: vince944red
Black stuff - can hide a lot as well as protect
White stuff is usually filler
Waxoyl is a brown colour and obviously waxy - you can't confuse it with black stuff.

Nobody has mentioned the best filler detector - a magnet, obviously a magnet does not stick to filler and if no force at all is felt on the magnet then there is no metal there at all either.

Cheers Vince! Hmmm! Probably leaves me even more unsure.

Does anyone have any decent photos of underneath their car up on a lift I can see for comparison?

 

[Super_Marv]

The black stuff is probably the original underbody protection which Porsche applied in the factory (or should that be Audi, with you 944 boys? [] ). It's probably turned black with all the dirt hitting it after all these years. Mine was a dark brown.

Sticking a digi camera in the sill is a good idea- I did that recently with my 968 and here's what it looked like inside:

You can see a bit of surface rust, towards the back, but towards the front, it's all fine. I've sprayed in some Valvoline Tectyl ML, which is the cavity wax Porsche uses AFAIK.

 

[Northern924]

Wow thats the cleanest inside shot I've seen, don't even want to see mine lol.

Must get some cav wax in there soon though after the repairs to keep on top of it

 

[pauljmcnulty]

Does anyone have any decent photos of underneath their car up on a lift I can see for comparison?

You won't tell much from under the car. It was undersealed when built, and this should have been regularly inspected and replaced if necessary, so it could well look perfect. Unless there's unusual damage underneath then you shouldn't have a problem.

The weak area is the inside of the sills, mainly at the back corner as in the great pics above. As the outside has a thick layer of underseal, then painted, it will hold together very well indeed, even when the inside has turned to dust. If it's not seen to, rust spreads from here to the inner sills, and the mounting points for the rear suspension and seat belts. Hence the MOT failure that is often a great surprise to people. [&o]

Aside from inspecting the car as you would any other, getting inside the sill and having a good look is the only way to have any idea what's going on. Thankfully Porsche built a handy access point into the door aperature. Any indie will inspect a car for you, or an MOT would give you a chance to chat to the inspector about general condition.