Does anyone know if a 1997 Explorer V6 4.0L with 3 timing chains is an interference engine?

Unfortunately, I'm asking this question AFTER one of the chains failed and because I'm getting conflicting information from different sources.

Thanks!

 

Are you sure it has three timing chains? It must have DOHC but why wouldn't they just run 2 long chains or belts?

 

Yes, it does have 3 chains, one for each cam shaft and one for a balance shaft.

Is there any tech manual that would tell me whether or not the engine is an interference engine, maybe the Haynes service manual?

 

Oh crud. So they added an extrashaft and chain too? They should havejust run one belt. Oh well - more parts more to have fixed (that's how they make a living these days). I wouldn't count on a Haynes manual - but you never know until you look. Finding things in a regular Haynes or Chilton manual is usually a hit and miss deal. Just for example I have the Haynes manual for 1991 to 2001 in front of me and I wouldn't have known your DOHC (Dual OverHead Cam) engine was in there because it's listed as SOHC (Single OverHead Cam) - which is impossible. Both cams are on the head and any way you put it that's Dual OverHead Cam. Whoever said it's an interference engine likely needs a trip down memory lane (or to an insane asylum). The only interference is minimal clearance at the timing chains and an integral main girdle and that the chains run down through the head. I must be missing something. But simply you have the 4.0 V-6 NON-pushrod engine.

 

Easier yet - 4.0 V6 DOHC.

 

Well, I was finally able to talk with a helpful person at a Ford dealership, who was able to look up the engine in a tech manual. Unfortunately, it is an interference engine, and it was damaged beyond what's worth repairing (had the mechanic pull the heads off and look). Apparently there was a TSB about some condition that could lead to the timing chain failing back in 2001 (which, we didn't recieve). Ford was willing to repair it for free for three years after issuing the TSB. Oh well, time for a new car...

 

Great nickname - I wonder still why they call it that though. Maybe the interference they're talking about relates to the timing chain? How bad was the damage? Did the front of the cylinder heads at the gears get busted up? Did the valves crash out? I'm just curious (if you have any idea).

 

Well, when the timing chain broke the the valves and piston heads tried to be in the same place at the same time. So basically the valves got trashed and there was apparently some additional damage that made the cost of repair = cost of a rebuilt engine = more than the car is worth.

 

You should look for a decent mileage engine at a cheap pricefrom a salvage yard - fix up the problem yours had so it doesn't occur again and drive. I picked up my last engine at a salvage yard in 1998 ( for $75) and put a couple gaskets, lifters and a new oil pump in. It's 2007 and I'm still driving with the same motor that had miles on when I bought it. It's a gamble - but was well worth $75 even if it'd blow up now.