29th Aug 2013, 16:49

I have a 1985 Cadillac Eldorado. A very, very good car. It needs some body work with 20,000 miles.

1st Sep 2013, 16:14

Is it accurate that these problematic 4.1 liter Cadillac V-8s can be replaced fairly easily with the reliable Oldsmobile 307 V-8? I believe that is the case in the rear wheel drive Cadillacs, not 100% sure about this model, but the 307 is found in the other cars on this platform - the Oldsmobile Toronado and the Buick Riviera.

28th Dec 2017, 06:30

That is fantastic news, that the Oldsmobile engine will fit into a 1985 Cadillac Eldorado, because I read that these 4100 engines are absolute junk. Any other comments about the 4100 Caddy engines?

28th Dec 2017, 16:21

Yes, the HT 4100 is one of the worst GM engines ever built, let alone it is THE worst Cadillac engine ever built. If anyone is interested in an Eldorado from this generation, my advice would be to ignore years '82-'85 and focus on trying to acquire years '79-'81.

30th Dec 2017, 03:47

My HT4100 went 129,000 miles before biting the dust. Not bad for a 'junk' motor. All these cars are antiques at this point, so even its 307 powered cousins (Riviera & Toronado) can potentially give loads of problems. I've found the 307 is tuned to be as gutless as can be and does not really perform better than the HT4100. Quality remanufactured HT4100s usually give years of reliable service and get better fuel mileage than 307s.

30th Dec 2017, 21:19

" loads of problems" on a 307 compared to a HT 4100? No way. Both have slow acceleration, but the 307 is an iron block/ head motor that can exceed the 300,000 mile mark with maybe a timing chain replacement for a major repair.

On the other hand, the 4100 was aluminum block/ iron head and was prone to head gasket, oil pump, cam shaft, rod bearing, block corrosion and oil pump failure. And they leaked out from just about every gasket.

It's a shame because all the 80s Cadillacs this engine was used in were some very nice, formal looking cars.

You can thank the 307 for saving the rear drive Fleetwood. That car was supposed to be done after 1985, but Cadillac borrowed the Olds engine and the car lingered on several years later.

5th Jan 2018, 00:10

You missed the point. The point is: vehicles 30+ years old can potentially have lots of problems regardless of what engine is in them. The 307 may be more durable than the HT4100, but that shouldn't matter at this point; unless you have the nerve to use a 30 year old car as everyday transportation.

Having owned an 87 Cadillac Brougham equipped with a roller lifter 307, I can attest to its durability. However the 307 is far from perfect, and just because they run doesn't mean they're not worn out and due for a rebuild.

Mine was burning excessive amounts of oil at the 180,000 mile mark, the intake gasket sprung a leak (common problem on these), crankshaft rear main seal was leaking oil, all the cylinders had compression well lower than normal. By 210,000 the timing chain slacked out causing the engine to surge. By around 230,000, #1 cylinder had lost all compression resulting in a permanent misfire - the engine was done. In actuality it needed a rebuild at 180,000 due to low compression, oil burning, and a top speed of 70mph.

6th Jan 2018, 17:00

So knowing the engine needed a rebuild at 180k, you drove it another 50k.

Sounds like you were pushing it to its limits or using the car as a beater.