4.0 longterm reliability

[Custom88]

I've heard from certain reviewers and from mechanics that the 4.0 V8 used in the Aurora is a nightmare when it comes to oil leaks and burning oil? I haven't seen any posts on this board though talking about this so I just have to ask if this is true or not. What are the common problems on the 4.0 that you have experienced and the cost to fix?
(IE. on the 3800 common problems are the alternator failing, leaking valve cover gaskets, and water pumps.)

[Aurora40]

I think the oil leaks are more prevalent on the early motors. 95-96 are more likely to have these issues. There were changes made to the engine to address them. Most oil burning that I've heard people report on was pretty much cured by proper fill techniques. The engine takes 7.5 quarts, and the dipstick is meant to be read hot. So it's quite common for people to put 8 or more quarts in which results in oil consumption. Add in the 6-7,000 mile oil change interval, and there you go. If you burned 1/2 a quart every 3,000 miles, you wouldn't care on a 3,000 mile oil change interval, but would suddenly care on a 7,000 mile one because you'd have to add oil. The same useage rate would suddenly be a "burner". Anyway, you get what I'm saying. I'm sure some do burn oil and some do get leaks. But from what I've seen, it's mostly as I described.

[stevensolds]

my 95 leaks a little. stealership wants 1800 to pull the engine and replace the seals. I dont think so!

[MpWarrior21]

My 97 also leaks but i havent had any time to see where it is acutally coming from.

[JimW]

The oil leak on the early Aurora 4.0 is not as bad as the amount of alternators that the 3800 eats, as well as the upper intake failure as well as the Dexcool issues due to the mixed usage of engine material.

The 4.0 is all aluminum and heats up quicker and according to some, heat is a premature killer of engine...I dunno, the 4.0 cooling system is pretty sophiscated.

The worst complaints I have heard....FPR, and oil leaks in the earlier models, I have yet to hear about an engine problem in the 2nd gen.

[LM]

My 96 does leak oil and has for about 3 years, about 35-40k miles. Like stevensolds, I was told a very large number to fix the problem......but it never has leaked any faster in the entire 3 years so I just keep an eye on the level.

[Marc]

After 4 years and 3 weeks, I do not see any oil leaks
anywhere in my 2001 4.0.
You have to consider that all of the problems that
cropped up with the early 4.0s were normal, because
this was a totally new engine design, something like
Olds had never made before, and you'll always run
into trouble in that instance.


________________

GM!!! BRING BACK OLDS!!!

[stevensolds]

Yep Marc could be a lot worse. glad it isnt, not for me anyway, er well not yet.. GM did a good job with the 1995+ L47 engine i'd say except a few minor things like the oil dipstick FFS but it could be like the pontiacs...throwing alternators left and right. That would be something i would not put up with.



Also depends how well the user takes care of his/her engine. Alumninum does heat up quicker jim but would you rather have a cast iron block that will fall apart in 10 years?

[Aurora40]

Actually, aluminum is a much better conductor of heat than iron. So an aluminum block will be better in the heat regards. Heat will be more evenly distributed across it so it should have less severe hot spots, and it can transfer heat to the coolant more efficiently. In addition, it can transfer heat to outside air better too, though I suspect this is not a large part of the cooling.

Aluminum heads on smallblocks in the '60s and even in the 90's lead to more power because the head was much more efficient at carrying away heat, thus they could run at higher compressions and power levels.

I believe there was some difference with the blocks being two part vs one part or just some change to the two part in 1996-97 or something that fixed the more common causes of oil leaking.