2003 Mazda B4000 w/ 305000 mi, original owner, making timing chain noise.
Replaced tensioners but no improvement and deciding whether to just fix what's wrong (pull engine and replace timing cassettes) or give it a new engine while it's out? I intend to keep the truck but have stopped driving it till fixed.
It's been a good engine, never failed and no problems except for the thermo housings.

Anyone with knowledge of FoMoCo re-man engines (how good are they?) where are they built etc. Would it be a top choice?
I'm finding many rebuilders won't do the 4.0 sohc - is going to the source the best move?

 

Welcome to the forum

Yes, once its making the "rattle" noise a timing chain guide is broken so new tensioner can't help
You need to change these 2 long chain tensioners every 100k miles, just FYI, easy to do

On any "new" or rebuilt engine check the warranty, many will not warranty the engine unless it was "professionally" installed, so DIY install voids warranty
If it doesn't say ASK, and get it in writing, like an email

Bottom end on most engines now-a-days(1990 and up) is 400+ k miles, 500k is not at all unusual
Pulling the engine and putting in new timing chains cassettes/guides, maybe pull oil pan and put in a new oil pump and redo gaskets , will be way less expensive
New Knock sensor(under intake)
New rear Main seal
You would be set for at least another 100k so 8+years, probably longer
Generally speaking if you were going to have valve issues it would have happened by now, after 200k
But no crystal ball here, lol

Ford crate engines are fine, well at least never read anything bad about them, its just the warranty thing, triple check

 

Great information Ron, and much appreciated - good news.
One thing I thought of is the possibility of shredded particles of plastic from the cassette getting into the oiling system -so I had wondered about pulling the oil pan and cleaning it while replacing the pump.
A suggestion I got was replacing the crank bearings while in there but I'm kind of hesitant to fix something that's not broken!
Thanks for the reply, very encouraging.

 

Yes, on cleaning the oil pan
No, on replacing lower end bearings, exactly, "if it ain't broken then leave it alone", except for rear main seal, lol, a cheap part that's hard to get to if it leaks

 

It has been my experience with race engines that rod bearings wear more than crank mains. I agree, if you have good oil pressure, no need to change crank bearings.

 

I always did regular oil changes and have good oil pressure, so I'll leave the crank bearings alone.
My first time posting to a repair forum - really great to get input from those who have done it!

 

I got mine in from a professional shop (Canada Engines). Timing chain(s) sounded loose from the getgo but they told me it was fine... yes I'm an idiot for not pushing the issue while the warranty was valid. I've put about ~60,000 km since and the sound has gotten worse at warm idle, and now is producing small bits of metal on oil changes. Not sure if it was an issue with the install or the remanufactured engine. It's not the same sound as the death rattle that killed my last engine, and the sound goes away at any rpm above idle.

 

Good info, thanks, and I feel your pain. Went to two local shops and they both quoted to install a nationally recognized name reman engine (not fomoco). One shop included in their quote the extended warranty offered by the reman company as well as the increased labor price coverage (when) it was needed to exchange the engine under warranty.
Gives you a bad feeling about those companies.
Because of not having the proper space to do the work I haven't done it yet, but plan to pull the engine and fix what's wrong - only. Reinstall and run it. If it was to be rebuilt I want that original core, not an engine assembled from parts bins.
If I was in your situation I would start getting ready to replace that engine before it quits - metal in the oil = bad news.
I would shop local wrecking yards for a core engine and ask around your area for a good rebuilder and have the core rebuilt.
In my area there's a guy who builds race engines. I don't need a race engine, but he must know how to do it right.
That's my guy.
Good luck.