What should I do regarding a high mileage engine/transmission?

[Evox]

I'm looking for the wisdom of others.

2004 ST 4x2, has 250k miles on it, including original timing chain cassettes. Currently showing no problems, except weeping oil out of the top valve covers, and at least the lower oil ban gasket and potentially the upper oil ban gasket (I can't tell if it's just from the valve covers or it is weeping too).

But when I say weeping I mean weeping. Not a drop of oil on the garage or driveway. Only noticeable if you look at the underside of the car. So it's just old gaskets doing what old gaskets do.

I've absolutely no problem pulling the engine, changing all the gaskets, and timing cassettes. By that I mean I have the skill, tools and time. But I won't lie, pulling an engine and doing all this is a pain in the ass, especially when I consider the mileage on the engine.

I could get a used engine that only has 71k on it, delivered for less than $900. Of course, while I had that "new" used engine out of the car I'd probably go ahead and do all new seals and gaskets and timing cassettes.

According to Carfax, the truck is only worth $3500 retail. Which holy hell isn't a motivating price for me to part with the truck. It basically has all new suspension components, has never been wrecked, and still looks, rides, and drives well.
So, what would you do?

1. Pull the existing 250k mile engine, which I've owned since new, and go ahead and replace all the gaskets, seals, and timing cassettes. While doing the valve covers and lower oil ban gaskets are easy, If I had to replace the upper oil pan gasket it'd be a hell of a lot easier on an engine stand. I'd also be able to replace the rear main seal while I'm there.

2. Wait until failure and deal with it then.

Thoughts?

 

[Todd Z]

Change the valve covers only, Ride it till it dies....

Or sell now while its still worth something.

 

[Duncan Kimbro]

I’m with Todd. I’d drive it until it fails, unless you can’t afford the unexpected downtime to replace the engine.

 

[Evox]

I appreciate the advice. I guess I'll just replace the valve cover seals, and maybe lower oil pan seal and drive her till she dies. I think I'll get an oil analysis done just to get some idea of where I am on this engine.

 

["Risky Bizness"]

How about building a new engine, THEN pulling the old engine. Next to zero down time.

 

[Evox]

How about building a new engine, THEN pulling the old engine. Next to zero down time.

That's not a bad idea.

However, a little research revealed that perhaps my experience isn't that unusual. Apparently Ford replaced their timing components after the 2002 Model year. 2003 and newer 4.0L SOHC motors have an updated and more durable chain guide. It's still a PITA engine out procedure to replace them but mine are still going strong. My motor purrs like a kitten from start-up. I did have to replace the thermostat housing last weekend after my old POS plastic one started to leak coolant at the rear seam. But after 15 years maybe I shouldn't complain.

I thought about getting the aluminum replacement, but I would have had to wait until next weekend, and the leak wasn't getting better. So I replaced it with another plastic one since that's all I could get locally.

At a certain point in car or truck ownership, it becomes a challenge to see how long you can keep your car running trouble-free. I'm at a quarter of million miles, so here's to half a million miles!