1998 Explorer with a blown engine.

[mikecmax]

I just bought a 98 Explorer and the compression on the driver's side is 60,30,60. Could this be timing chain?

 

[snoranger]

If its a 4.0l SOHC, Then YUP, good chance the chain jumped or broke.

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the stock 95-01 section.

 

[mikecmax]

Thanks to all who know anything about 4.0l SOHC engines. It looks like a nightmare. I am going to start looking at it today or tomorrow. Thanks for the move also.

 

[2000StreetRod]

Remove the valve cover

I suggest that you remove the valve cover and inspect the guide assembly for damage and check for correct timing.

For an explanation of the timing chain configuration see My Helpful Thread: Rear Timing Chain Tensioner Replacement

For the Ford procedure for timing the camshafts see My Helpful Thread: SOHC V6 Camshaft Timing

If you have tools and some mechanical ability don't be afraid to perform the task yourself. Post your progress and questions and you will receive plenty of assistance from this forum.

 

[mikecmax]

I just finished reading the first 4 pages of your saga and I find it very informative. I was already going to remove the cover and have a look today or tomorrow. My roomie wants to swap motors but I would rather find out what is wrong before doing anything.

 

[McSlug]

If you performed the compression check yourself and you can read then you have the qualifications to work on this engine.

Don't just rip everything apart in a quest to find answers. Do some research. There are some great step by step procedures on here some with very helpful pics. There are many many things to disassemble and a good procedure will help in putting it back together.


You must gain a full comprehension of the timing set up, how it works and how they are connected. This is the key to simplifying the procedure and avoiding time consuming and costly mistakes. Learn this before you touch anything.

I have basic mechanical knowledge but thanks to the people on this site I replaced my front timing components without issue.

I wish you luck and hope you end up with a sweet running Ex

 

[mikecmax]

This was going to be my first step. I want to find out what is wrong before I do anything.

 

[McSlug]

In the case of a bent valve. Some people have opted to replace the engine due to the cost of head work. Keep this in mind when evaluating your costs. Cost's change from location to location so it is hard to get a good opinion on what is best for you.

Personally I see replacement engines as a last resort for 2 main reasons.
1: You may be buying the same inherent issues.
2: Pulling your old engine to fit the replacement is most of the work and nowhere near as satisfying.

 

[mikecmax]

To McSlug:

You just said everything.

 

[2000StreetRod]

Slipped chain

I suspect that after you get the left valve cover off you will find that your timing chain has slipped due to a broken upper guide assembly. To check the timing first rotate the crankshaft clockwise (never counterclockwise) to have #1 piston (front right cylinder) at TDC (use the pointer on the crankshaft position sensor and the crankshaft dampener) on the compression stroke. You can tell if #1 piston is on the compression stroke by checking the protrusion on the left camshaft for the camshaft position sensor. The protrusion should be pointed upward as shown in the photo below by shelbygt.

Then check the orientation of the camshaft timing slot on the rear of the camshaft. It will be difficult to check because of the close proximity to the firewall. The slot should be below the centerline of the camshaft and parallel to the head surface that mates with the valve cover as shown in the photo below by shelbygt.

If the slot is off try and estimate by how many degrees and in which direction. If it is more than 50 degrees you may have sustained valve damage.

If the front guide assembly is broken then you will have fragments in your lower oil pan and oil pickup tube screen.

 

[mikecmax]

Thanks. I'll let you know what I find.


Well it took 2 hours to get the rad out. The Haynes book said the drain was on 1 side and it was on the other.
It never mentioned I couldn't see it till I took off a cover that wasn't mentioned. It also said the 5.0 had an intercooler but so does this 1. I only mention these minor things cause it is so hard to get up after I lay down under the car.

 

[mikecmax]

I decided to test the compression on the passenger side but found it impossible to get at plugs 2 and 3 without removing AC drier. Tested #1 and got 55 lbs. It's back to removing valve covers.

 

[mikecmax]

I can't find all the bolts on 4.0l sohc intake manifold. I can't climb up and need locations and other info. HELP!

 

[2000StreetRod]

Removing valve cover & compression test

I can't find all the bolts on 4.0l sohc intake manifold. I can't climb up and need locations and other info. HELP!

There was no need to remove the radiator to remove the valve cover. Go to My Helpful Thread Starting my 00M12 Installation

On the first post is a link to some thorough step by step instructions on removing the upper intake manifold. My thread supplements those instructions.

When you perform your compression test are you making sure that the throttle plate is at WOT? If not, the results are invalid.

 

[mikecmax]

I took the rad out because I would need it off to take the timing chain cover off or pull the motor.
I redid the compression test and got a rousing 58 psi instead of 55.
Thanks for the link to manifold removal.

 

[2000StreetRod]

Spark plug access

You should be able to remove the right spark plugs by removing the wheel and the inner flexible flap.

58 psi on cylinder #1 does not sound good. When you get the right valve cover off you'll probably find the traction side of the guide assembly is missing as shown in the photo below.

It should look like the photos below.

 

[mikecmax]

8 hour shift. Not used to working. Retired 3 years.
Got upper manifold off only broke 1 small clip.
Got driver's side cover off.
Cam sensor node is at the top. Slot on other end is parallel to the head and on the lower side of center.
It looks like there is no guide. compression 60,30,60.
I just do not understand.
Tomorrow I will take off the passenger side cover.
I think I need a nap.

Thanks for the help on the manifold. There was a little hose covering the back 2 screws.
I will look at the plug thing tomorrow also.

 

[2000StreetRod]

Puzzled

If the valve stems were bent and the valves not seating I think the compression would be zero. If the head gasket was blown then I think adjacent cylinders would have very low compression. Did the previous owner provide any description of the engine symptoms other than it was blown? Did it run at all?

Are any of the valve springs broken?

The timing of the left camshaft sounds correct even though there is no guide. It is possible that the valve springs have pushed the camshaft into the correct position to relieve valve spring pressure. You might try manually rotating the crankshaft clockwise while watching the camshaft to see if it starts moving at the same time. If the crankshaft rotates and the camshaft doesn't immediately then there is slack on the traction side of the chain because of the broken guide assembly and the timing reading is invalid. The traction side (the one with no hydraulic tensioner) must be taught to check the timing.

 

[mikecmax]

You're puzzled! What about me?

My roommate pulled on the tensioner side with a little puller low on the chain and there was little slack. I suppose he should have pulled on the other side.
The previous owner had it towed to a dealer and they got it going. They drove it to a gas station and put gas in it.
It died at the gas station and has not run since.
I had to go out and test the chain. I could not deflect the chain on the drive side no more than 3/8 inch.
I think this is not too much. Or is it.
Last note : Everything looks so confusingly normal. No broken springs nothing to indicate anything wrong.
More tomorrow.