Compression testing advice / Help

[onemanonelaptop]

Hi everyone,

Really could do with some help

I have a 99 explorer with a suspected timing chain slip/break....

I have just done a compression test and have got ZERO across the board, not even a sniff of the needle moving...

I want to check ive done everything right and am not misunderstanding the process:

1. I have removed all spark plugs
2. i have removed the fuel pump relay
3. I have disabled the sparkplugs

I have in turn attached the compression gauge to each sparkplug hole in turn and then cranked the engine approx 5-10 rotations. Belts turn etc.

Each cylinder shows ZERO.

Was my procedure correct and does this mean that every valve is bent? I was kind of expecting a reading of some kind even if it was low....

Thanks for your help in advance.

PS: ive tested the gauge on an air line and its working.

 

[rasouth]

Did the engine run before you started this procedure? If so I doubt all your valves are bent. It sounds as if your compression tester is not hooked up properly. I would make sure the compression tester is screwed in tightly into the spark plug hole. Some testers come with different sized threaded ends for different sized plug holes. Make sure you use correct size.

 

[1998Exp]

Hi everyone,

Really could do with some help

I have a 99 explorer with a suspected timing chain slip/break....

I have just done a compression test and have got ZERO across the board, not even a sniff of the needle moving...

I want to check ive done everything right and am not misunderstanding the process:

1. I have removed all spark plugs
2. i have removed the fuel pump relay
3. I have disabled the sparkplugs

I have in turn attached the compression gauge to each sparkplug hole in turn and then cranked the engine approx 5-10 rotations. Belts turn etc.

Each cylinder shows ZERO.

Was my procedure correct and does this mean that every valve is bent? I was kind of expecting a reading of some kind even if it was low....

Thanks for your help in advance.

PS: ive tested the gauge on an air line and its working.

Probably won't make a difference in your case, but the throttle needs to be fully open

 

[Mbrooks420]

You’ve got a faulty, or leaking gauge. I’ve never seen a multiple cylinder engine with zero compression across the board.

 

[C420sailor]

Put your thumb over the spark plug hole while a buddy cranks it. That’ll tell you if your gauge is shot or not.

All plugs out, wide open throttle.

If you suspect timing is out (she jumped teeth) then a compression test may not give you accurate results—your valves on the bad bank may be open at TDC.

 

[onemanonelaptop]

You’ve got a faulty, or leaking gauge. I’ve never seen a multiple cylinder engine with zero compression across the board.

hmm..I tested the gauge on an air line to be sure and it checked out ok.

Put your thumb over the spark plug hole while a buddy cranks it. That’ll tell you if your gauge is shot or not.

All plugs out, wide open throttle.

If you suspect timing is out (she jumped teeth) then a compression test may not give you accurate results—your valves on the bad bank may be open at TDC.

Ive got the rear chain exposed and the cassette and chain looks in tact.... I'm looking to expose the front chains now..

 

[onemanonelaptop]

So here is what i can see with a camera looking down the sparkplug cavity....

 

[vroomzoomboom]

hate to say it but your gauge may not be incorrect. you have bent valves

 

[onemanonelaptop]

hate to say it but your gauge may not be incorrect. you have bent valves

Yup ive put the camera in all 6 and they've hit the cylinders across the lot.... Do i even bother at this point going the repair route or do i just put another engine in....

 

[vroomzoomboom]

Me personally, toss it, find another 4L. That came in explorers, Rangers amd mustangs. I’m just finishing up a motor that I put in a ranger and did the chains on. To me in the past it’s cheeper and faster to put a different motor in with lower mileage

 

[onemanonelaptop]

Me personally, toss it, find another 4L. That came in explorers, Rangers amd mustangs. I’m just finishing up a motor that I put in a ranger and did the chains on. To me in the past it’s cheeper and faster to put a different motor in with lower mileage

The only option i have for a replacement has done 118k, this one died at 70k with a snapped primary chain. I have no warranty on the replacement just have to hope its as described, i cant seem to find a complete list of parts required for a full rebuild (which is what id do if i was going to)....

 

[Mbrooks420]

The only option i have for a replacement has done 118k, this one died at 70k with a snapped primary chain. I have no warranty on the replacement just have to hope its as described, i cant seem to find a complete list of parts required for a full rebuild (which is what id do if i was going to)....

Can’t find a comparable 4.0 out of a Rover?

 

[St. Louis Explorer]

So here is what i can see with a camera looking down the sparkplug cavity....

View attachment 330965

How did you take the picture?

With a flexible camera tube (Endoscope) or your cell phone?

I am disabled and I could only get the 2 back spark plugs on the driver's side out of my 99 Explorer XLT 4 Door 4X4 Auto 4.0 SOHC 184,x.. miles and I used my thumb over the holes while my neighbor rolled the engine over and nothing. I had first used an Auto Zone Loner Compression Tester and got nothing and I thought it was bad so I did the thumb test. The truck starts right up, races to 2300RPM and then dies. It will not start again until the next day and does the same thing.

The back plug had the correct spark plug gap (.054) but the middle plug had a gap of .032 and looked like it had been hit by something to bend it down?

When the truck starts right up you cannot tell (hear) that it is not firing on all 6 cylinders but it starts right up and races to 2300RMP and then dies even with the 2 spark plugs out...

Does anyone know of a good deal on an Explorer in the St. Louis, Mo. area that I can buy?

I don't have any credit so I need a cash deal under $5000.

Does anyone know of a good mechanic that does side jobs here in the St. Louis, Mo. area that I can contact to work on this truck and/or future repairs on my next vehicle?

Is this considered bad manners asking all these questions on this fellow's post?

Should I start a post of my own?

Thanks,
Bob