Notice for all Newbies considering buying an E9 coupe / rust warning / steps to inspection / BEFORE YOU PURCHASE

[paul cain]

Recently I have been involved in four Coupe inspections, some before the sale, some after.

Three of the four cars were cosmetically presentable but suffered from really substandard metal work and paint work. In two of these cases the owners have substantial investments in their projects and are not pleased to hear that their foundation is cracking and slipping into quicksand.

I am appalled at the low quality metal work on these recent examples. I would like to offer an early warning alternative to any newbie considering buying their first Coupe. See attached.

Being pillarless, these unibodies are highly reliant on the lower sills for their structural integrity. These sills had really poor drainage designs (particularly sunroof examples) and are the second most common area for rust accumulation on E9s. When they 'go' and lose their integrity it is exceedingly difficult and expensive to recapture the original integrity.

Before you buy a Coupe it is your responsibility to inspect this structural integrity. With values increasing there are more and more examples of fast paint and interior jobs showing up in the marketplace, with astonishing transaction values.

Request the seller to provide you the attached 10 views of the subject Coupe. This is some work as the decorative lower sills (both) have to be removed. If the seller refuses, do not proceed. If the seller is reluctant offer to share the expense of the sill R&R in the following manner –“I will commit to a conventional PPI if the rust images are provided and there is no structural rust’’. There is no point in proceeding with a PPI if the car is compromised.

The attached 10 areas are ranked in importance, you might not be able to get all 10. But the first five are the bare minimum. You guys can debate the ranking 'till the bondo dries.

Do not buy a coupe until you have these images. And you have had the images inspected or have had an experienced shop pass judgement. One more time kids..... Caveat Emptor.

 

[JMinPDX]

Priceless information. Well done sir.
BTW my coupe is rust free in all 10 areas you cover. That‘s what the PO‘s son told me.

 

[Erik]

Seems like this should be part of a "How to buy/How to sell a coupe" section added to the "where they rust" page. Maybe a list of all sections to check and examples of photos to take for sellers or PPI mechanics who aren't experts.

So many coupes offered with just "beauty" shots and no real metal disclosure anywhere on their interweb ads or auctions. Without them, the real question has to be, "What lies beneath?" And obviously, some buyers are not taking the time to find out until the money is gone.

BTW, is there a way to see inside the rocker structure without disassembling it?

 

[Gary Knox]

Well done Paul. Definitely weak spots that should be investigated.

 

[craterface]

Sticky this thread!
Paul, we have not met, but I know of your long experience with vintage BMWs.
I made this video to show how one can get a glimpse of the inner fender cavity from below, even without a borescope.

Also, how does one remove the rear fender/shock tower liners in the trunk without destroying them?

 

[Markos]

Rocker surgery:

 

[bmw2800cs]

Recently I have been involved in four Coupe inspections, some before the sale, some after.

Three of the four cars were cosmetically presentable but suffered from really substandard metal work and paint work. In two of these cases the owners have substantial investments in their projects and are not pleased to hear that their foundation is cracking and slipping into quicksand.

I am appalled at the low quality metal work on these recent examples. I would like to offer an early warning alternative to any newbie considering buying their first Coupe. See attached.

Being pillarless, these unibodies are highly reliant on the lower sills for their structural integrity. These sills had really poor drainage designs (particularly sunroof examples) and are the second most common area for rust accumulation on E9s. When they 'go' and lose their integrity it is exceedingly difficult and expensive to recapture the original integrity.

Before you buy a Coupe it is your responsibility to inspect this structural integrity. With values increasing there are more and more examples of fast paint and interior jobs showing up in the marketplace, with astonishing transaction values.

Request the seller to provide you the attached 10 views of the subject Coupe. This is some work as the decorative lower sills (both) have to be removed. If the seller refuses, do not proceed. If the seller is reluctant offer to share the expense of the sill R&R in the following manner –“I will commit to a conventional PPI if the rust images are provided and there is no structural rust’’. There is no point in proceeding with a PPI if the car is compromised.

The attached 10 areas are ranked in importance, you might not be able to get all 10. But the first five are the bare minimum. You guys can debate the ranking 'till the bondo dries.

Do not buy a coupe until you have these images. And you have had the images inspected or have had an experienced shop pass judgement. One more time kids..... Caveat Emptor.

View attachment 109358

Super helpful, this is the highest priority item on my list, I actually would like a seasoned person to inspect my car in the San Francisco bay area. SFDon reccomended someone. I will definitely look into these spots!

 

[day66]

Might be worth mentioning checking the roof skin on cars with a sunroof?

 

[teahead]

#3 area...is that also visible from looking through the glove box/fuse box doors?

 

[Gary Knox]

A little history lesson here for those of you who may not have been driving e9's 45-50 years ago!!! However, the only 'examination' on the subject will be in your garage!

From my experience back in the late '70's, early 80's, the first place rust starts to show visibly is in area #3 in the document above. Paint bubbles about an inch or two above the rocker started to show when my '73 was about 8 years old (first owner for 3 years in Boston area, I had it next 2 years in Charlotte NC, then ~3.5 years in southeast PA. ). The car had about 55K miles on it at that time. Sold it a few months after the rust bubbles appeared.

Gary

 

[sandhu]

Recently I have been involved in four Coupe inspections, some before the sale, some after.

Three of the four cars were cosmetically presentable but suffered from really substandard metal work and paint work. In two of these cases the owners have substantial investments in their projects and are not pleased to hear that their foundation is cracking and slipping into quicksand.

I am appalled at the low quality metal work on these recent examples. I would like to offer an early warning alternative to any newbie considering buying their first Coupe. See attached.

Being pillarless, these unibodies are highly reliant on the lower sills for their structural integrity. These sills had really poor drainage designs (particularly sunroof examples) and are the second most common area for rust accumulation on E9s. When they 'go' and lose their integrity it is exceedingly difficult and expensive to recapture the original integrity.

Before you buy a Coupe it is your responsibility to inspect this structural integrity. With values increasing there are more and more examples of fast paint and interior jobs showing up in the marketplace, with astonishing transaction values.

Request the seller to provide you the attached 10 views of the subject Coupe. This is some work as the decorative lower sills (both) have to be removed. If the seller refuses, do not proceed. If the seller is reluctant offer to share the expense of the sill R&R in the following manner –“I will commit to a conventional PPI if the rust images are provided and there is no structural rust’’. There is no point in proceeding with a PPI if the car is compromised.

The attached 10 areas are ranked in importance, you might not be able to get all 10. But the first five are the bare minimum. You guys can debate the ranking 'till the bondo dries.

Do not buy a coupe until you have these images. And you have had the images inspected or have had an experienced shop pass judgement. One more time kids..... Caveat Emptor.

Thxs for the info

 

[Mal CSL 3.0]

This is great info Paul.

Just had one suggestion to add. In the front footwells there are plastic plugs both sides that can be easily removed to see inside the chassis rails.

I recently had a look in side my rails (can use a borescope). If they still have original paint inside the rail which is a primer colour and still waxoyl covering in place that is also a good sign for the general integrity.

(Excuse the poor 1980's welds on my floorpan btw)

 

[pickman]

All really good info and detail. had my coupe for 43 years and replaced most of the sheet metal in the post. However many of the issues were not visible until all the paint was removed to bare metal. Good job!

 

[Cornishman]

Great work. Also the above two videos are also excellent.
Only after buying mine did I really understand the rust issues, but got lucky. I had a good look on a ramp, but not like proposed here.
Happy to say that when I removed the sill covers and wheel arch covers that all was good.

 

[teahead]

can't imagine paying more than $25k w/o a PPI for this stuff.

Way too many perfumed pigs out there selling for huge dollars.

 

[Markos]

My thoughts via wall of text. Read away if this stuff interests you. Too long to check spelling and grammar. I'll review later.

I have my own theories on how these cars degrade. I'm not a CS expert, but I have spent a good amount of looking at rusty coupes including two of my one. Here they are by number. At a high level, gravity plays a role in a lot of the rust areas.

1. This area rusts from driving the car in the rain. If your car has low miles or wasn't driven in the rain, this area will be find. That includes cars that sit outside in the rain. The rust comes from the bottom up, not the top down. Rain that lands on the top (say from a car sitting outside) will run down the gutter towards the headlight area.

2. Rocker rust happens from both driving and sitting. Lots of chatter about sunroof drains. The front sunroof drains land in the front of a rocker near a drain hole. That will certainly rust out. The rear sunroof doesn't drain anywhere near the rocker. It drains behind the rear wheel wells. This is a common misconception. All E9's sunroof and slick top have c-pillar drains that empty to the back of the rocker. I'm still not quite sure how water gets in there, other than working through the various sheet metal folds or a bad windscreen seal. The little holes underneath the c-pillar emblem go to this drain. All drains need a vent, just like your kitchen sink and toilet. This is the vent for the rear rocker drain. If you remove the rear fenders, you will see that there is actually a stamped metal funnel immediately behind the c-pillar emblem.

3. The fender box can rust from driving and sitting, but will be more susceptible to driving. My car for example sat outside for a good 10 years. There is a low point in the inner fender near the firewall connection where water can pool. Eventually you get pinholes here that turn to holes. The water drains into the fender box with no place to go. If you drive your car in wet snowy weather, the holes start from the inside. Once the pinholes open up on the top, the problem will escalate. To see how severe this area is, examine the sheet metal from inside the car, behind the glove box and oddments tray (fuse box door). On more severe cars, this will begin eating away at the fender well portion of the firewall, the small curved piece near the kick panel. On my parts CSI, I could nearly crawl through this hole and the fender box was completely absent. Conversely, the windscreen frame is perfect. In fact, I cut off the frame and kept it.

4. Rust forms here from driving. As others mentioned this is one of the first areas to show rust. The thin gauge fender is sandwiched against a beefy a-pillar. Rust that forms here isn't necessarily a leading indicator to major rot elsewhere. I spoke about this in the (1974 mint green mintgrun) thread - a car now owned by BMW veteran @halboyles who saw the light at the end of the tunnel. In this thread, I highlighted that with the kick panels removed, one can actually inspect the backside of the A-pillars quite well. The biggest area with the A-Pillar is the small portion that overlaps the rocker 'membrane' (see Classic Heroes video that I linked above). The small portion of the lower A-pillar is available from W&N, and quite inexpensive. As is the lower fender piece. Labor on the other hand - best wishes!

5. Rust on the floor pan will happen from driving and sitting. When old cars sit however, the window seals dry up, crack, and shrink. When water hits the glass it will inevitably pool on the floor. The rust will from from the inside out, manifesting in the paint drain caps. Cars with bad floor rust will have separation of the floor pan to inner rocker.

6. I've yet to see a rusty upper shock tower. Again, gravity prevents any pooling in this area. Splashing from tires will cause a problem, but that is on the inner fender wells (particularly the front of the well under the rear seats), not the upper shock tower. On a side note, many people discuss the rear shock towers blowing out. The fact is that the vast majority of cars have their original shock towers intact. I've seen a few folks on the forum with repaired towers, as well as a friend in town. I think it is another example of over emphasized concern, but is something to seriously consider when selecting the valving on your rear shocks.

7. Just like the floor pans, the rust in the wheel well will be from sitting, or failure to replace the boot seal, and tail light gaskets. It is also one of the easiest parts to replace. As of about 3-4 years ago, W&N offers a replacement lower portion. The walls (again due to gravity) rarely need addressing. If you purchase a coupe that restored in the '90's or 2000's, it will often have an E3 or other BMW spare wheel well.

8. The A-pillar will rust due to a failed seal. In particular, the passenger side lower frame. I believe that this is mostly due to sitting in the rain, based on the poor condition of my car. Conversely, my CSI had completely shot (everything), but the windscreen frame was original and completely rust free. SO a car that saw a lot of miles to a car sitting in the rain, and the sitting car took the hit. There is something to be said about the passenger corner. This is the area where the passenger side (LHD) wiper pushes rain down. That happens in the center of the frame also with the driver's wiper, but the rust isn't present. The difference is that the corner is where the seal begins to pull away from the metal. The corner is where the aluminum trim begins to lift. So you have the combination of the wiper forcing half of a rainy windscreen into this area. For this reason, you'll see this area as a problem on driven cars and parked cars. The parked cars however are likely just due to the seal lifting in this area. You liekly won't find a lot of rust along the sides of the A-pillar, unless the windscreen seal was heavily neglected.

9. This is one area that I'm not sure about. I see cars heavily rusted in this area, and also cars with heavy rust on the door tops near the chrome sill trim. I'm not sure what causes rust in this area. Neither of my neglected cars had major rust on the nose, or the chin. I suspect that chin rust is due to driving, and nose rust is due to sitting/gravity.

10. This is another guaranteed problem area. I believe that is mostly due to driving, as it is actually a high point in the floor structure. However, a compromised fender box will eventually open to the firewall, and water will drain in this area. So if you have a sitting car this area will be the path of travel from the shock tower, to the fender box, down the firewall, to this area, and then to the paint drain on the floor panel.

 

[Markos]

Other observations:

I've been working with a member who is evaluating his rockers. I'll post a video of my scary rusty rocker for folks to see. I think that most of the rocker rust commentary really comes down to the value of the car, and being careful not to overspend. If you buy a cheap E9, say sub-$30K (as of 2021), the rust situation becomes less of a concern. You can drive a car with rusty rockers. In fact a good chunk of the e9 community is doing this now, whether they realize it or not. You can drive car with a few holes in the pan or tunnel. You can drive car with visible rust bubbles (as many do as well). There is a point where you shouldn't likely park the car, but that point is likely more severe that one might assume, especially one from individuals that have not dealt with severe rust and rot.

I read some advice on bringatrailer from a long-time self-proclaimed CSL expert and forum member from the mountain region. He stated that a good way to test the rockers is to jack the car up. I can state from personal experience that this does nothing to determine the integrity of the rocker. I jacked my not-fit-for-the-road CSI up by the nearly absent rockers numerous times. I regularly jack my CS up by the subframe pickups, and my incoming video will strike fear in to the eyes of any California auto enthusiast. The fact is that steel is very strong, but also very forgiving. It takes a lot of rot, and missing material for the car to start behaving differently. Now keep in mind, I'm speaking of casually driving the car, not getting involved in a collision. As far as that goes, I practice the "safer than a motorcycle" mindset.

One area that I think is more concerning than the rockers is the upper shock towers. When you browse through cars, you will see subtle evidence of the shock towers working their way to the hood. When they completely give way, they will extend up past the hood line (as noted on my parts CSI: deconstruction-thread-how-to-part-out-an-e9). At any rate, I've seen many '74's in particular that suffer from inner fenders migrating north over time. This is evident by rub marks at the peak of the shock tower. The butyl sound deadening will have wear mark on it. I have made note of this one one of my fenders, but it isn't as severe as what I've seen on BAT. I will add my own pics later, as am happy to expose all skeletons in my closet. Going back to value, I can transparently share rust on my car because I paid $3K for the car, knowing full well that it had problems that I will enjoy tackling. The price point is nothing to celebrate. The car will be a headache to restore. With that said, the ROI on it is still a lot higher than most BaT offerings for the motivated enthusiast. It is understandable that not everyone wishes to point out the warts on their car, even if they may have overpaid. They are just cars. They aren't a window into or soul.

I am not trying to pick on this car, or the owner. I hope that they are present and chose to comment. The car is lovely, and sold for $100K. However, it is one of many e9 examples of migrating inner fenders. I'm not talking about hood alignment either. The inner fender tops extend above the fender lips. It is a common E9 problem, but rarely discussed. Review below, then go look at your coupe and freak out!

Note the worn butyl on the passenger side inner fender crest, near the outer fender.

Note the corresponding wear mark on the hood:

Note that although minor, the crown of the driver's side inner fenders extends above the outer fender lip:

 

[Eric V]

@Markos writes “I think that most of the rocker rust commentary really comes down to the value of the car, and being careful not to overspend. If you buy a cheap E9, say sub-$30K (as of 2021), the rust situation becomes less of a concern. You can drive a car with rusty rockers. In fact a good chunk of the e9 community is doing this now, whether they realize it or not. You can drive car with a few holes in the pan or tunnel. You can drive car with visible rust bubbles (as many do as well).”

Well said, rust advice often seems oversimplified to “never buy an E9 with any rust” which leaves us spending $80-120K or just never buying an E9. You can still enjoy the E9 experience with a car that mostly hides its rust well, you just don’t want to overpay.

 

[Stevehose]

Rear shock towers bust from metal fatigue not rust, been a well documented issue since the early 80’s.

 

[Markos]

Rear shock towers bust from metal fatigue not rust, been a well documented issue since the early 80’s.

I totally agree. That is why I mentioned valving. My point is that it isn’t as common as people think. I know yours blew through. Also, unless a crack hasn’t been addressed, it’s not a major PPI concern. I can’t think of anybody that would pass on an e9 due to a previously repaired shock tower. It is good to call it out, but a very minor detail in the grand scheme of things.