Post
I found a BMW E30 coupe with an S54 swap, but the car has quite a few issues and I’m not sure whether it is still worth buying. The car started life as a 1984 318i and currently has around 270,000 km on the chassis. The owner says the S54 swap was done about four years ago, and that the car has only been driven around 15,000 km since the swap. The listed modifications are: S54B32 engine swap Sport mode button. When activated, the car feels faster. The owner claims it adds around 10+ horsepower, although I’m not sure if that is accurate or if it only changes throttle response. 6-speed transmission 5-lug hub conversion 3.45 limited-slip differential E60 brake system Full chassis bracing / strut bars / reinforcement bars Body reinforcement has been done Rondell 0058 wheels Opening rear quarter windows Sunroof E36 Recaro seats E46 steering system Multimedia steering wheel Aftermarket audio system When I inspected the car, I found several things that concern me: The front strut towers have some rough-looking areas. I’m not sure if they are welds, seam sealer, or some kind of reinforcement work. The owner says it was done to strengthen the body. I attached photos and would appreciate opinions on whether this looks acceptable or worrying. The owner said he modified or adjusted the cooling fan setup. The fan seems to work very hard, and he also said that after stopping, he lets the fan run for about one minute before shutting the engine off. This makes me worried that the car may have cooling issues. One of the rubber boots on the steering rack is torn. When the car was lifted and inspected from underneath, I saw oil dripping from above the steering rack on the left side. The owner said it is just a leaking hose and that he will fix it. The LSD/differential has some oil seepage. It is not dripping heavily, but it is visibly wet. The owner said it needs to be opened and serviced. The engine mounts are Chinese parts, and the front subframe appears to be custom welded. The subframe sits about level with the oil pan. The owner lowered the car. I do not recognize the brand of the front shocks, but the rear suspension uses Bilstein shocks with Eibach springs. The car is very low. The lowest parts of the mid-pipe and rear exhaust section sit slightly lower than the subframe, so the exhaust has many scrape marks. During the test drive, I noticed that the fuel gauge dropped when cornering. Also, the owner casually shut the car off and restarted it while waiting at a red light. He said that sometimes while driving, the throttle stops responding, and the car needs to be switched off and restarted. The owner says the ECU is from an E46 M3, but it is installed inside the center console, so I could not see it. He also said the car is currently making less than 300 hp. Because of the throttle issue and the strange fuel gauge behavior, I suspect there may be an ECU, wiring, tuning, or fuel system problem. However, the owner says that replacing the ECU for around $2,000 would solve the problem. Another concern is that the owner cannot provide photos from when the swap was done. I don’t know how serious these problems are. I’m worried that if I buy the car, I may end up in an endless repair project. On the positive side, at least during the 10-minute test drive while I was in the passenger seat, the car was able to drive and felt very strong. The asking price is close to $20,000, which is not cheap. However, in my country, this is still the best-condition two-door E30 I have been able to find, and I really like the aggressive character of the S54 engine. Do you think these issues are serious enough that I should negotiate the price down with the seller? I am mentally prepared to spend another $5,000 fixing and sorting out the car after purchase, but if the cost of properly addressing these problems goes much beyond that number, it would be difficult for me to afford. I am also prepared for higher running costs, such as more frequent oil changes and using higher-quality / higher-spec oil. I recently got a more stable income, so I think I should be able to handle the maintenance costs in the future. Would you consider this car worth buying, or are these warning signs serious enough to walk away? What specific areas should I check before making a decision? Sorry for the long post, but I’m seriously considering buying this car and I don’t have many local experts who understand E30/S54 swaps. I attached photos of the areas that concern me. If anyone has experience with E30 chassis reinforcement, S54 swaps, cooling systems, or custom subframes, I would really appreciate your opinion. Even small details you notice in the photos would help me a lot, because I’m trying to avoid buying a car that turns into an endless repair project.
Intent Score
0
Intent
99
Confidence
Summary
The post is about evaluating a modified BMW for purchase and has no meaningful connection to window replacement or window issues.
Reasoning
This is clearly a car-buying/mechanical inspection discussion, not a homeowner window problem, comparison, or replacement inquiry. The mention of "opening rear quarter windows" is incidental to the vehicle and not relevant to residential windows.
Extracted Signals
- car purchase topic
“Is this S54-swapped E30 still worth buying despite these issues?”
- automotive inspection details
“I found a BMW E30 coupe with an S54 swap, but the car has quite a few issues and I’m not sure whether it is still worth buying.”
- irrelevant window mention
“Opening rear quarter windows”
Model: gpt-5.4-mini · Prompt: v3 · 6/11/2026, 5:01:58 PM