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No compression in 4.0 SOHC

Sharky146

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Hello everyone. I'm working on a project Ranger and need a little help. I picked up a 2001 Ranger XLT Supercab 2WD 4.0L for $200. The previous owner said he thought that the timing was bad. I check the compression and had zero compression in any cylinder. So, I pulled the motor and opened it up and the timing cassettes and tensioners had basically disintegrated. The chains were still on the sprockets, but I figured they probably jumped timing since there was no longer any functioning tensioners or guides.

I replaced all the timing components with the Cloyes timing kit. I also bought the special set of timing tools required to time the Ford 4.0. I reassembled the motor and timed it using the special took kit, but I still had zero compression in ALL cylinders. I thought maybe I had set the timing 180 degrees out, so I just went back and swapped both cams 180 degrees and reset them using the special tool set. However, I still have ZERO compression in any cylinder.

FYI, I'm just using a socket and 1/2 ratchet to turn the motor to check compression. In the past I've always used the starter while the engine was installed in the vehicle to check compression. But, I should still get compression with just a ratchet and socket, right??

Any help would be greatly appreciated.
 


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MikeG

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No. Use the starter. There's gaps in the rings and the valves will never seal perfectly unless you just did a valve job.
 

Uncle Gump

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If the timing of the valve train indeed jumped... these are interference engines and it probably bent valves in each cylinder.

I'm guessing you didn't pull the heads?

It's to hard to get any cranking speed using a socket and a ratchet...
 

Bgunner

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You said you checked the compression before pulling the motor. Did you use the starter then?

If you did and there was no compression then the likely reason is what Uncle Gump mentioned and the pistons bent the valves which means at minimum a top end rebuild or a motor swap is needed. Many times if a piston hits a valve it takes out both the piston and the valve.
 

Sharky146

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I did not pull the heads just because I didn't want to deal with having them machined, etc. However, maybe I need to pull them now? I still have the engine out of the truck. I've got it mated to the tranny, so I can reinstall the starter and hotwire it with a battery if you think that's a good idea to do a compression check. I imagine I'd need to add engine oil if I was going to spin it with the starter.

So, I won't get ANY compression with a ratchet and socket? That seems weird. In the past, I've turned other engines with a ratchet and socket and could at least hear the hissing of the air exiting the spark plug holes. But no air sound coming out of this one.

I thought these 4.0s were non-interference?? If the valves did smash into the pistons, I imagine I'd need to have the heads redone with new valves, right?
 

Sharky146

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Bgunner, I didn't see your reply prior to sending my last post. I guess I'll need to pull the heads and see what damage I've got in there.
 

Sharky146

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Yes, I used the starter to check the compression before I pulled the motor. Zero compression.
 

Bgunner

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In that case my money is on needing a complete rebuild or a motor swap. You can pull the heads but I'm sure that you have bent valves in all cylinders.
 

Sharky146

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In that case my money is on needing a complete rebuild or a motor swap. You can pull the heads but I'm sure that you have bent valves in all cylinders.
Gotcha. I'll pull the heads and have a look. Besides cracked pistons, what else should I be looking for under the heads? If the valves were bent, does that mean the heads are shot, or can they be rebuilt with new valves and guides?
 

Uncle Gump

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A lot of times... they are pretty much scrap.

Pull the heads and see what you have... and access the damage and get prices.

In the end... you might be looking for a used engine... but before you put it in... put all your new timing components on... then install it.
 

Bgunner

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The heads usually can be rebuilt but not always. Look at the valve seats, where the valves touch the heads, any gaps means it wont seal. valve springs and seals should be done as well as the valves and guides, so a good amount of money involved compared to a junk yard motor. Dings in the heads of the pistons means the pistons will need to be replaced or they will burn through and you will be back inside the motor doing a low end. The dings create hot spots and that creates the melting of the piston heads surface. Bang a hole is created.
 

Sharky146

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The heads usually can be rebuilt. Look at the valve seats, where the valves touch the heads, any gaps means it wont seal. valve springs and seals should be done as well as the valves and guides, so a good amount of money involved compared to a junk yard motor. Dings in the heads of the pistons means the pistons will need to be replaced or they will burn through and you will be back inside the motor doing a low end. The dings create hot spots and that creates the melting of the piston heads surface. Bang a hole is created.
Ok, thank you for the info. I'll pull the heads and have a look. If everything is in bad shape, I'll likely send her to the junkyard. She's not worth a rebuilt motor and it seems like these 4.0s had a lot of timing problems, so I'm not sure I want to take a chance on a junkyard motor. I'll keep you posted, and thanks again.
 

Bgunner

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The timing issues with the 4.0 is due to its miles of timing chain and some need to have the motor pulled to do them so people push them to far and you end up with a boat anchor. You already have the timing kit to fix the timing issues in a junkyard 4.0 motor so unless the rest of the truck is in desperate need of a lot parts it is still worth the money for a motor.
 

Roert42

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She's not worth a rebuilt motor and it seems like these 4.0s had a lot of timing problems, so I'm not sure I want to take a chance on a junkyard motor.

They are pretty reliable motor, you just need to change the tensioner every 70,000, which is a fairly easy maint item. Most people just don't do it. I just recently bought one with 250K and i can't really find any problems with the motor.
 

Sharky146

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I pulled one head and it looks like the exhausts valves are all bent. There are some light witness marks on the top of the cylinders, but nothing that really look too bad to me.

I called my local head shop and he said it would cost about $350-400 for a valve job and to have them resurfaced. Plus the cost of new valves ($10-15 each). He said that if the seats need to be redone it’s $50 for the first one and $15 for each addition seat. I think I might bring the heads to him and have him take a look. If I can have him do it all for about $500 it might be worth it.

Your thoughts?
 

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