2004 Explorer timing cassettes replaced, engine just "spins"

[PapaMelch]

Hello everyone. I've been learning and following all the posts to repair the exploded timing cassettes in the Ford 4.0L SOHC. Replaced the left, right, and front cassettes, all were in pieces, and I replaced the tensioners. I got everything back together (finally after 6 months!). When I turn it over the motor just spins instead of the familiar "I wanna start, I wanna start" that you would expect to hear. The first time I had it back together (a couple weeks ago) I turned it over and the engine just spun like that. I came back here and read some more and realized I didn't time the cams right (had the cam slots slanted instead of parallel with the head surfaces) so I went back in and timed them again. I lined up the timing mark on the harmonic balance and then set the cams timing slots exactly parallel with the heads, off center slots lower side down.

One thing I noticed, when you rotate the crankshaft one full revolution to get back to the timing mark on the harmonic balance, the cams are upside down (off center cam slots now on the upper side). Is it possible to time this off by 180 degrees in relation to the crankshaft? If so, how can you tell which way the cams are supposed to sit?

Thanks in advance, pulling my hair out
Melch

 

[koda2000]

The TDC mark on the crankshaft damper goes around twice before the camshafts make one full revolution. That's because there are 2 top dead centers on a 4-stroke engine. Once for the compression stroke and once for the exhaust stroke. If the engine is just spinning and doesn't sound normal it's because the valves aren't closing. This could be because you originally timed the cams incorrectly and banged your valves into your pistons bending them and now you have no compression. I hope I'm wrong, but that's my guess.

 

[PapaMelch]

The TDC mark on the crankshaft damper goes around twice before the camshafts make one full revolution. That's because there are 2 top dead centers on a 4-stroke engine. Once for the compression stroke and once for the exhaust stroke. If the engine is just spinning and doesn't sound normal it's because the valves are closing. This could be because you originally timed the cams incorrectly and banged your valves into your pistons bending them and now you have no compression. I hope I'm wrong, but that's my guess.

Thanks for the reply Koda. This brings up the famous question, "is the 2004 an interference engine"?. Haven't found a straight answer yet. When this engine blew, it made all kinds of racket. My original thought was that it threw a rod. Then I found this forum and pulled the engine to find the cassettes were wasted. When I first looked at it, I rotated the crankshaft by hand. The crankshaft timing chain was slipping and not spinning the cams so both cams went out of time in relation to the crankshaft. When I rotate the engine by hand now, there is no resistance, no tapping or other sounds when I crank it. When I set the right cam into position, the intake valve rocker was loose on #1 piston, the exhaust wasn't. This is how I figured I had it in the correct position. Originally, before doing anything, the left cam appeared to be sitting close to the proper position, cam slots on the lower side, so I kept it there and timed it.

 

[koda2000]

Yes. It is most definitely and interference engine. And I meant to say the valves aren't closing...

 

[david4451]

Without taking everything apart, you should get a boreoscope and look at the top of the pistons through the spark plug holes. You should be able to see valve marks on top of the piston if contact was made.
You can also do a compression test on each cylinder which will tell you if valves are sealing properly.
I fear the worst since you said it was a very noisy failure, hope I'm wrong and good luck with your findings.

 

[PapaMelch]

Thanks for the reply Koda. This brings up the famous question, "is the 2004 an interference engine"?. Haven't found a straight answer yet. When this engine blew, it made all kinds of racket. My original thought was that it threw a rod. Then I found this forum and pulled the engine to find the cassettes were wasted. When I first looked at it, I rotated the crankshaft by hand. The crankshaft timing chain was slipping and not spinning the cams so both cams went out of time in relation to the crankshaft. When I rotate the engine by hand now, there is no resistance, no tapping or other sounds when I crank it. When I set the right cam into position, the intake valve rocker was loose on #1 piston, the exhaust wasn't. This is how I figured I had it in the correct position. Originally, before doing anything, the left cam appeared to be sitting close to the proper position, cam slots on the lower side, so I kept it there and timed it.

Without taking everything apart, you should get a boreoscope and look at the top of the pistons through the spark plug holes. You should be able to see valve marks on top of the piston if contact was made.
You can also do a compression test on each cylinder which will tell you if valves are sealing properly.
I fear the worst since you said it was a very noisy failure, hope I'm wrong and good luck with your findings.

David, thanks, I'll see if I can find a boreoscope.

If it turns out that I have bent valves, what am I in for to fix it? I've never done valves before. I never did timing chains before either but I'm mechanically inclined so I can handle it. The engine that's in there is a replacement and cost $1800 with installation. I suspect the original engine blew due to the same problem. This replacement engine didn't last long at all. I have $700 invested into the parts I replaced already and 6 months (when I had time) of work. I'm hesitant to buy another used engine since these are prone to this problem and I've already committed to fixing this one. What do you guys think? Could something else be wrong that would come and bite me after putting effort into the valves?

 

[koda2000]

Your looking at major expense and labor. Assuming you've checked both sides and have found bent valves (a very likely scenario) You're looking at removing both heads and everything that entails, taking them to a machine shop to see if there's any damage besides just the bent valves. Then you're looking at fairly expensive machining, new valves, seals, gaskets and head bolts.

Most people would have thrown in the towel after having the timing chain failure on a Ford 4.0L SOHC. It's the main reason you find so many 4.0 SOHC's in the junk yard. You say you're "mechanically inclined" but the 4.0L SOHC is not the easiest engine to work on, requiring special tools and knowledge. Many on this forum have reported poor results after spending thousands of dollars to have a professional mechanic do major engine repairs (and they're supposed to know what they're doing, though I have little faith in most mechanics).

Even if you manage to do all this work correctly yourself, the Ford 4.0L SOHC is not a particularly reliable/desirable engine. I understand that you've put a lot of money into this vehicle to-date, but IMO trying to repair/replace the cylinder heads you may be following your soul down a rabbit hole. If you love your Explorer you might be better off cutting your loses on this one and looking for a decent V8, If you don't love it, look for a clean Honda Civic. Any used car is likely to have it's share of issues. I'm just trying to give you a reality check.

Edit:
I just realized we're talking about an '04 ST, which makes a difference as they're with quite a bit more than an Sport of 4-dr. This doesn't change the fact that it's a SOHC or a big job, but it does make a difference as to whether it's worth fixing. If it were me I think I'd be looking for a rebuilt engine with a warranty.

 

[PapaMelch]

Your looking at major expense and labor. Assuming you've checked both sides and have found bent valves (a very likely scenario) You're looking at removing both heads and everything that entails, taking them to a machine shop to see if there's any damage besides just the bent valves. Then you're looking at fairly expensive machining, new valves, seals, gaskets and head bolts.

Most people would have thrown in the towel after having the timing chain failure on a Ford 4.0L SOHC. It's the main reason you find so many 4.0 SOHC's in the junk yard. You say you're "mechanically inclined" but the 4.0L SOHC is not the easiest engine to work on, requiring special tools and knowledge. Many on this forum have reported poor results after spending thousands of dollars to have a professional mechanic do major engine repairs (and they're supposed to know what they're doing, though I have little faith in most mechanics).

Even if you manage to do all this work correctly yourself, the Ford 4.0L SOHC is not a particularly reliable/desirable engine. I understand that you've put a lot of money into this vehicle to-date, but IMO trying to repair/replace the cylinder heads you may be following your soul down a rabbit hole. If you love your Explorer you might be better off cutting your loses on this one and looking for a decent V8, If you don't love it, look for a clean Honda Civic. Any used car is likely to have it's share of issues. I'm just trying to give you a reality check.

Edit:
I just realized we're talking about an '04 ST, which makes a difference as they're with quite a bit more than an Sport of 4-dr. This doesn't change the fact that it's a SOHC or a big job, but it does make a difference as to whether it's worth fixing. If it were me I think I'd be looking for a rebuilt engine with a warranty.

It's the 4dr XLS 2 wheel drive, the engine is out of a 4wd.

 

[koda2000]

It's the 4dr XLS 2 wheel drive, the engine is out of a 4wd.

Oh, as you posted in the Sport Trac sub forum I assumed it was an ST. In that case my initial comments apply.

 

[PapaMelch]

Oh, as you posted in the Sport Trac sub forum I assumed it was an ST. In that case my initial comments apply.

Oh, as you posted in the Sport Trac sub forum I assumed it was an ST. In that case my initial comments apply.

Yeah, I'm new here. I posted it here as well: http://www.explorerforum.com/forums...placed-engine-just-spins.448068/#post-3549178

 

[PapaMelch]

I finally used a borescope and all of the pistons have been tagged. Time to consider if replacing the heads is worth it.

 

[koda2000]

I finally used a borescope and all of the pistons have been tagged. Time to consider if replacing the heads is worth it.

Probably not when you add that to all the other parts you're going to need. Cheaper to get another engine.