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Timing chain tensioner failed are the heads ok?

Cstoliker

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2000 Exploder XLT 4WD 4.0 SOHC.
Rear (right) timing chain tensioner failed as well as the cassette (or whatever the tensioner pushes against). Turned the engine over by hand and the timing chain (visible through the tensioner hole) appears to still move with the crank. Does this mean that the engine is still good and didn’t crush or bend the valves?

I could justify removing the engine and replacing the timing chain & cassette. But replacing the heads would be a death sentence.

F000-ED0-D-C83-A-43-AA-BCA0-66-C8-B081-EB3-B.jpg
 
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fast_dave

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@Cstoliker
First 2 photos made it through - BUT the second 2 didn't - suggest you again.

If it doesn't work, try Imgur as your hosting service.
Hope that helps w/ the photos! :thumbsup:

As far as the SOHC problem - I imagine the only way short of taking off the heads and doing a manual/visual inspection of the valves would be to do a compression test; but at this stage of the game I dunno if rotating the engine with the starter motor and thus possibly introducing damage to an undamaged head(s) is the safe thing to do...

I'm a OHV owner - BUT - there are lots of SOHC owners who have been there, done that, and can offer great advice through their experience with this engine.

Forum participants@donalds and @J_C have SOHC's and come to mind right off the bat.
Hopefully they'll check in soon, see the alert to this thread, and chime in!

In the meantime, since it's a SLOW Holiday Weekend, use the SEARCH feature to this forum, and also check out:

The Ranger Station / 4.0 Liter Forum - Link:
4.0 Liter Forum

Ford Truck Enthusiasts 4.0 Liter Forum:
2.6, 2.8, 2.9, 4.0 & SOHC 4.0 V6 - Ford Truck Enthusiasts Forums

I hope all this helps and good luck/report back and close the loop!
 
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J_C

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I have never done this repair but have a few thoughts...

What were the symptoms, were you just getting a sudden, or progressively worse chain rattle? Was it still running, and was it running okay or badly, or did it suddenly die?

If it was still running with a smooth RPM then you may be lucky and the timing chain didn't jump any teeth. First thought is I would disconnect the battery, pull the spark plugs, pull the belt, and rotate the crankshaft by hand/wrench to see if there's any resistance like a piston's hitting a valve.

If you happen to have a borescope you can also look down in the cylinders. Some of the fancy ones have upwards-looking mirror tips you can use to maybe see the valves, but otherwise I'd expect that you'd see at least a mark on the piston if there was a collision.
 
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koda2000

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The only way you'll know if your valves got whacked is to pull the head and that's going to require you to remove the engine from the truck because you said the right side tentioner & cassette failed. My guess is your valves on the right side are likely bent. If you can bring each bank 1 cylinder up on the compression stroke you might be able to use a leak-down tester to see if the valves are sealing to confirm valve damage, but the engine still must come out to replace the right rear timing components.

Removing the engine and taking it apart are huge jobs, especially on a rusty vehicle. Replacing the the timing chain components requires special tools and good quality TC parts are expensive.

I'm in the process of pulling the Job 2 SOHC engine out of my '01 Sport Trac because my rear cassette is broken and I have a blown head gasket. My engine was running good before I took it off the road and I have literally zero rust to deal with. Still, it's been quite a struggle getting the engine ready to pull (3 trans bolts are all that remain). I'll see what I find when I take the engine apart. I'm hoping it will be salvageable but we'll see. Even if the engine can be repaired I'm figuring at lease $2,000 in parts, tools and me doing the labor.

Not trying to be a "Debbie Downer" but that's what your up against.
 
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Cstoliker

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It was running with a rattle, then it lost almost all power. It still starts are runs but requires heavy throttle to keep running and barley moves under it’s own power. Definitely not smooth. I was kinda hoping that with the tensioner failed the cam rotated just enough to unsync the valves without doing actual damage.
Did not know if there was enough free play for the chain to jump a tooth.
 
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koda2000

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It was running with a rattle, then it lost almost all power. It still starts are runs but requires heavy throttle to keep running and barley moves under it’s own power. Definitely not smooth. I was kinda hoping that with the tensioner failed the cam rotated just enough to unsync the valves without doing actual damage.
Did not know if there was enough free play for the chain to jump a tooth.

Doing the leak down test will confirm bent valves or not. What usually happens is they do jump-time. Mine rattled at startup unless I brought up the oil pressure first using the starter motor and slightly while running, but it never jumped-time. I was surprised to see no cassette at all when I removed the passenger side valve cover, just chain and the tensioner. I imagine I will find all the broken plastic cassette pieces sitting on top on the upper engine girdle when I take it apart, because there was nothing found in the oil pan.
 
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donalds

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Hell I got nothing to add ;) and j_c and koda a nailed it all :thumbsup:
Pull the heads look for marks if there is :banghead:
New or remanufactured are in order ...when you pull em fill the combustion chamber with gas with the valves closed if they leak they are bent ....
Pulling heads is a must
If you do the job we are here to help no problem ps have fun or why do it at all its a big job
 
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drdoom

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Put the engine at TDC compression stroke of cylinder #1, and pull the valve cover. Check the position of the alignment slot on front of camshaft. That will show you if the timing jumped.
 
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boominXplorer

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Remove the camshaft so the valves are closed and use a compression tester (with Schrader valve removed) and air line to pressurize the cylinder. You shouldn't feel or hear any air out the exhaust or intake but you will hear it blowing by the rings into the crankcase.

Trying to turn the motor over any more could cause damage. With the rear guide broken the is enough slack by the jackshaft for it to lay in there and jump teeth. Either way the engine has to be removed.
 
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J_C

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Trying to turn the motor over any more could cause damage. With the rear guide broken the is enough slack by the jackshaft for it to lay in there and jump teeth.

That seems pretty unlikely. Any damage would be far more likely to have already occurred running the engine, while turning it by hand has just about zero chance of causing damage because you're barely applying any torque and can stop if any resistance is met... unlike using the starter to turn it over. There won't be any if you've pulled the plugs.

Plus the chance of jumping teeth either already happened or is again far less likely by hand than something like an RPM deceleration event when it was running.

I'm not suggesting such a test is proof the engine is good, but rather it would be a first test to see if there's evidence it's bad, isn't viable for just a timing chain/tensioner/cassette repair.
 
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boominXplorer

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I've bent valves on one of these with bad chain guides just turning it over to pull the transmission. I thought it was compression I was fighting but definitely wasn't. The engine was junk to me but it definitely happened. Of course if you remove the plugs there shouldn't be any resistance but it doesn't take much to bend a valve when turning it over.

When turning over by hand your putting inconsistent pressure on the chains. When you relax to turn the ratchet back the cams can flop forward or backward because they don't have any tension on them and the rear chain has plenty of room in the jackshaft gear area to do it. When using the starter the tension stays tought on the chains the whole time until it starts.

Turning the motor any more is a risk. I'd pull the valve covers and check the timing before turning the motor to pull it out(has to be done no matter what) then look and see what you got. If you pull the cam before turning the motor no matter what the valves are up and won't bend. Remember that rear cam bolt is reverse thread.
 
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allmyEXes

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Somewhere on this forum within the past year, I saw a picture of a 4.0 SOHC with the heads off and you could see the single mark of each valve on the top of the 3 pistons that I think was caused by the exhaust valves hitting the pistons.
Can anyone confirm this? ad possible original poster direct me to the picture?
 
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allmyEXes

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Thanks! That was a quick find.
Yesterday I ordered 3(4) exhaust valves Melling V1914 and RA only sells them in pairs of exhaust valves not singles
 
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koda2000

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Doing the leak down test will confirm bent valves or not. What usually happens is they do jump-time. Mine rattled at startup unless I brought up the oil pressure first using the starter motor and slightly while running, but it never jumped-time. I was surprised to see no cassette at all when I removed the passenger side valve cover, just chain and the tensioner. I imagine I will find all the broken plastic cassette pieces sitting on top on the upper engine girdle when I take it apart, because there was nothing found in the oil pan.

Update to my SOHC engine saga:
After engine tear-down, I found my balance chain tensioner was destroyed. That explained the noises (clicking and slight chain rattle at times) I'd heard in the front of the engine and the small piece of spring steel I'd found in the oil pan. I was surprised to find that my engine even had a balance shaft as it's a RWD Expl. My front cassette was completely still intact, but my rear cassette was broken into multiple pieces. My engine did not jump time so no valve/piston damage, but I need to have my heads checked to find the source of the exhaust leak into the cooling system. On cursory inspection I don't see anything obvious on the MLS head gaskets. It's possible that I may need to replace at least 1 head. If I'm lucky the heads will just need to be resurfaced. Right now I'm on hold with a medical issue, so I can't work on the engine for a while. I hope to get back to it soon.
 
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koda2000

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Hope all is well @koda2000

Thank you. It's not huge deal, just something that doesn't allow me to be on my feet right now. Going to see the podiatrist on Thursday. Sucks to get old.
 
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410Fortune

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grabs tools and heads to Koda's house Ill rip that SOB out of there for you!
Dang sohc engines and all those chains!!
 
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