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1979 bmw 528i

My car recently turned over 120,000 miles. I have owned her for 5 years. Currently, the engine temperature gauge needle is moving all over the place. It typically registers the correct temperature (I think), but sometimes it goes all the way over to the red, then peaks and falls back down to the midline. Before this started happening, the needle would lie just below the midline when traveling on the highway and just above the midline when driving in town. Yesterday, it was lying between the 1/4 mark and the midline – much lower than normal. Is this as simple as just replacing the temperature sensor? My mechanic noticed a month ago that the transmission hoses are all swollen and in need of replacement. Is this related?
One more thing, within the last week, the electrical system fails while driving, but just for a second. I can tell because the radio goes out. Once, it went completely dead, then came back on within 2 seconds. It made me think of the alternator, but it seems if that were the case it would go dead and not come back on, no?
Thanks in advance for your advice!

It’s not unusual to have several problems at once with a 32-year-old car. Intermittant electrical failures are not likely caused by the alternator. A bad alternator makes you battery go dead, but not all at once. It could be a bad/loose/corroded connection(s), especially the battery cables and clamps. The temperature gauge problems could also be caused by bad connections, a bad sensor, or maybe problems in your cooling system. Get the transmission hoses replaced soon, if they blow you’ll be stranded.

While that age 528i is my favorite old BMW, they require LOTS of upkeep. Do you have a good “old BMW” mechanic?

Thanks for you comment.
The battery connections look good to me, so I am perplexed by the car cutting out. I can’t find a rhyme or reason to it. It seems to happen when I first start it up, but also while driving down the road.
Do you think the temperature sensor ought to be replaced? They are inexpensive, but is it a difficult installation? I watched a youtube video about it and they said you needed to drain the radiator. Is this true for my car as well? What kind of problems in my cooling system might it be? I did notice that while driving yesterday that the area around my feet was quite hot, like the heater was on, but it wasn’t.
I used to have a fantastic “old BMW” mechanic in Portland, OR, but now that I have moved to the east coast, I’m am doing some repairs on my own, with my mechanic in Portland as my phone a friend life line. I will call him today.
I love my car and want to keep it as long as I can. I haven’t had any major problems in 5 years, also not much upkeep. I am trying to make it last as long as I can. I don’t mind investing in her, since so far it has been much cheaper than a monthly car payment. My Portland mechanic says she’ll run for 300,000 if I take care of her. Do you agree?

While it certainly could go 300k, it’ll cost a fair amount of money to do it. You really need to find a decent local mechanic. You might start with the BMW forums, they’ll be able to help direct you. And there might also be a local branch of the BMW car club of America in your area, they’ll be a good resource. Keeping old cars (what used to be called ‘antiques’) running requires as many contacts as you can get.

While I could guess about your problems, that’s all they would be. It really sounds like you need to find a mechanic, have him give the car a thorough inspection and come up with a list of problems and the cost to fix them. We can help you decide which to do first.

As for the battery clamp looking OK, the cables can corrode internally, causing problems. But only a close look can tell.

Sounds good. Thanks for your help!

One more thing - now that you’re on the east coast, you’ll need to watch for rust, if you’re in the northeast. Rust can kill your 528i long before the engine gives out.

You need to check more than just the connections at the battery. Check both ends of the +/- cables from the battery. Any other connection could be a little corroded, too.

Your engine temperature problems and your tranny hose problems could be related. I believe that in this vehicle the tranny cooler is contained within the radiator structure, like two radiators in one. If you have leakage between the engine cooling system portion and the tranny cooler portion, the engine coolant will be diluted/depleated by tranny fluid, your tranny fluid will be diluted.corrupted by coolant, and your tranny lines will be pressurized and heated by the engine coolant. This could account for your engine cooling problems and affect your tranny and its cooling lines. I’d suggest that you get this checked out ASAP, and because your tranny may be on the verge of destruction from the fluid cross-transfer, you may even want to have it towed.

The electrical problems could conceivably be caused by sporatic engine shutdown, and might even be related to the other problems you’re describing. Coolant corrupted by tranny fluid could be allowing the engine to overheat and it may be binding and momentarily shutting down. Just as the car would keep rolling if you shut the engine off forr a moment, the engine shutting down momentarily may be be readily felt by your seat.

I strongly recommend that you get this to a BMW shop ASAP. If I’m right, every mile counts.

TSMB, if you’re right, the ‘auto recycler’ might be the next stop…hope you’re not!