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Discussion Starter · #1 ·
Hi All,

Sorry for the long post - trying to include all details! Love this forum.

So I've got a 2003 Disco with 105k. Recently had shot intake and valve cover gaskets with significant coolant leaking, minor oil leak. Took to trusted independent shop specializing in Land Rovers and had them complete the following work:
-New intake gaskets, valve cover gaskets, and head gaskets
-Machined heads
-New spark plug wires (Magnecor 8mm), Bosch Platinum+4 plugs
-New water pump
-New tstat

NOTE: The heads were machined – but actually, they contract with a machine shop and I received heads that were already machined and ready to go from another vehicle. So not my original heads. These heads are warrantied/guaranteed to be free of defects.

Another NOTE: Prior to service, the front passenger side O2 was going bad (saturated in oil and coolant from valve cover and intake gasket leaks) so I would have rough idle. Voltage near 0 all the time.

After the work was completed, no leaks – bone dry underneath. Truck drove great except there was a noticeable rough idle right out of the shop which I assumed was still associated with the bad O2. It was a little worse than normal though. A few miles into the drive home, I start throwing misfire codes. SES light also started flashing. Never had a misfire code before on this truck before the work. Truck still running great when not idling – really smooth on the highway actually.

Pulled codes and got P0300, P0305, P0306, P1300, and P1129 (O2)

I took it back to the shop and they tried the following:
-I actually found a bolt was missing on the passenger side header. They fixed, but didn't resolve the issue
-Compression test – cylinders fine
-Pulled spark plugs, cylinder 5 and 6 were wet with gasoline, totally dead, not firing
-Checked vacuum lines, checked plug wires, coil pack
-Confirmed it is not a fuel injector, mechanic actually swapped them from other cylinder and same thing occurs only on 5 and 6
-Confirmed not bad spark plug, mechanic switched Platninum+4s for NGKs. Replaced all spark plugs at no cost to me. Same issue
-Checked MAF sensor, doesn’t appear to be any issue
-Mechanic says coil pack is fine, he's 99.99% sure (from what I’ve also read, it would be rare for only two cylinders to fail if coil pack is bad? – though I did read that Magnecor wires may exacerbate problems in ignition system that were not as evident before with lesser quality wires?)

Finally the QUESTIONS for you 
-Could the bad O2 be causing the misfire codes (one on each bank??) – I’ve asked them to change out the bad O2 as next step.
-Mechanic mentioned it is possible for the “core to shift” when doing this type of work, and it is unavoidable, which could be causing the codes (does this sound correct?)
-Since I didn’t have any codes before the work, what is the likelihood it’s the new heads (not from my vehicle)? They should have been tested by the machine shop as they are guaranteed
-Is it possible the new heads just need time to “settle”? Any thoughts that this could actually get better based on the work completed if I continue to drive it?

There is the gamble that if they tear it down again to check the heads for defects – IF there is an issue, this would all then be on the machine shop and they would have to pay to get me up and running again. If not, I would definitely be stuck with some hard choices.

Any thoughts on anything we could have missed?

THANK YOU
 

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When you installed the new O2 sensors, did you thoroughly clean the oil and gunk off the connectors? This can cause codes if the connectors are fouled. I would check this first.

Plugs not firing? No idea. Someone on the forum should have something to advise.
 

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Another NOTE: Prior to service, the front passenger side O2 was going bad (saturated in oil and coolant from valve cover and intake gasket leaks) so I would have rough idle. Voltage near 0 all the time.

After the work was completed, no leaks – bone dry underneath. Truck drove great except there was a noticeable rough idle right out of the shop which I assumed was still associated with the bad O2.
Don't see anything to indicate you addressed the 02 issue prior to shop repairs. If you continue to get light and codes they may be totally unrelated to repair done by the shop. It's quite possible that now the other problems have been repaired you're simply seeing additional emission related codes that should be addressed before your cats are damaged.
......
 

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Discussion Starter · #4 ·
Don't see anything to indicate you addressed the 02 issue prior to shop repairs. If you continue to get light and codes they may be totally unrelated to repair done by the shop. It's quite possible that now the other problems have been repaired you're simply seeing additional emission related codes that should be addressed before your cats are damaged.
......
Thanks! Can one bad O2 really cause misfires on BOTH banks? E.g. front O2 bank 1 could cause misfire on cylinder 5 and 6 (bank 1 and 2)??

Either way, changing out both front O2 sensors today to be extra safe and will report back ASAP. Will make sure connectors are cleaned.
 

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Discussion Starter · #5 ·
OK replacing the bad O2s made no difference with the misfire other than its idling a *little* less rough. Still the same misfire codes p0305 and p0306

So it seems its something mechanical

What do you think I'm looking at? Camshaft? Since the two cylinders are adjacent to each other (5 and 6)?

The frustrating part is that there was no issue before the head work (other than intake gasket leak). Redoing the top end somehow brought a problem out of hiding on the bottom end?
 

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Is it possible that you did not read the major sticky "a MUST read for anyone about to repair head gaskets or valve train noise" ???


If you are positive it is not fuel, not spark, compression is good and your "trusted independent specialist" has not forgotten any other bolts it sure seems that you very likely have a block leak.
Is that what you guy is referring to as "core shift" ? If it is I would think that anyone familiar with these engines would expect a strong likelihood of a cylinder liner leak. These engines are notorious for it.
I am currently re sleeping my 2002 with "Darton flanged sleeves from Turner Engineering in the U.K.
Those not familiar with them they are world renowned Land Rover engine specialists.
If it is a sleeve leak and it sure sounds that way you are likely looking at $3000 to $5000 in parts and machine shop services, above and beyond what you have already put in it (I'm guessing you spent in the ballpark of $3000 so far)
That does not include re doing what you have already done.
 

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Discussion Starter · #8 ·
Is it possible that you did not read the major sticky "a MUST read for anyone about to repair head gaskets or valve train noise" ???


If you are positive it is not fuel, not spark, compression is good and your "trusted independent specialist" has not forgotten any other bolts it sure seems that you very likely have a block leak.
Is that what you guy is referring to as "core shift" ? If it is I would think that anyone familiar with these engines would expect a strong likelihood of a cylinder liner leak. These engines are notorious for it.
I am currently res leeching my 2002 with "Darton flanged sleeves from Turner Engineering in the U.K.
Those not familiar with them they are world renowned Land Rover engine specialists.
If it is a sleeve leak and it sure sounds that way you are likely looking at $3000 to $5000 in parts and machine shop services, above and beyond what you have already put in it (I'm guessing you spent in the ballpark of $3000 so far)
That does not include re doing what you have already done.
Thanks - will read the sticky. I still trust the indy based on my past experience with them

But wouldn't a cylinder liner leak have have had some symptom before this work (e.g. never had a misfire before this)? Would the cylinder liner leak on one cylinder affect the opposite cylinder (e.g. 5 and 6)?

Yeah, at $5k I would just get a new remanufactured engine from Atlantic British with the flanged liners.

So unfortunately my options now are:

1) Hoping there is a clue in only two, opposite cylinders beings affected (5 and 6). Camshaft? Crankshaft? Sorry - this is where my knowledge of the engine isn't as refined and looking for some help. E.g. arent the connecting rods for opposite cylinders basically on the same spot of the crankshaft? Maybe a bearing issue?

2) Sell the Disco for peanuts even though the rest of it is in great condition

3) Put a new engine in it with flanged liners (approx $7500 with labor)
 

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I'm thinking that the coil pack isn't bolted down. 2 bolts in the top, 2 more in the bottom. If the bottom 2 bolts aren't holding the coils securely to the block, you will get misfires. Check it out. You may need a mirror, flashlight and page 454 in the Rave manual (number 30 is the 2 bolts that people will disregard) so you know what to look for.
 

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The centre 4 cylinders (#3 ,4,5 and 6 seem to be the biggest area of weakness and sleeve/ block failure mine was #4 and a bit in #3 . #4 was "steam cleaned" when it came apart top of piston looked as clean as new. A horoscope down the spark plug hole would show it.
IF it was a bearing,it would knock and rattle and generally sound BAD all the time and more so at speed.
Your question and statement that it never did it before all the work was performed is a good one..... What is different ?
Spark is good plugs are new X 2 all the same.
Fuel supply and injector is not the problem
Compression is "good" how good is good? Would be good to have actual numbers

So assuming all is good, what is different ? Cylinder heads are different! Maybe good, guaranteed etc. But different

I have not yet had to perform it BUTTurner Engineering and others in the know, strongly recommends checking / shimming the rocker shafts!
measurement of the pushrods and checking the stem height of the valve are also strongly recommended steps as part of a reassembly (again points covered in the "sticky" I mentioned earlier related to heads, head gaskets and valve train noise.
Too loose = valve train noise
Too tight = valves not fully closing high hydro carbon, failed emissions testing, eventual valve damage.

If they did not check, adjust, shim the rocker shafts it IS possible ???????

Dealer diagnose? Not likely ! They will likely charge you hundreds of dollars to tell you it needs to come apart. If you trust you guy stick with them and push them for answers! As you said "it never did that before all the work was done"
 

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Discussion Starter · #12 ·
Update: Stopped by the shop on the way home last night, checked out the disco, and got some new info. I misheard and therefore misrepresented one key fact on here previously (my bad - I am having shop send me all the numbers via email now)

Compression on cylinder 5 and 6 is actually *not* good.

Here are the latest developments:

-"The compression in cylinders 5 and 6 was around 50. The other ones are where they should be with a minimum of 160"
-There are NOT any metal flakes in the oil.
-After the car was warmed up, as it was cooling down we heard a very distinctive "click" or "snap". The mechanic noted he had heard this too previously when it was cooling down. I noticed this noise only happened twice - and it sounded like once on each bank. This has never happened before the service.
-This noise, combined with the update on compression again leads me to believe the issue is mechanical
-They are going to going to do a leak down test again and send me the results. Based on the above, I think they need to do it when engine is both at operating temp and cooled down

I think redtruck12 is on the right track - I am imagining a stuck exhaust valve when hot that "snaps" back into place after its cooled?

Will report back on the leak down test

I think I need to push them to redo the work with my own heads. Before the work was done, it was never mentioned to me that the machined heads would be from another vehicle. If I had known this, I would have just waited and told them to get my heads machined.

For reference, attached are what my old heads look like and the new heads from another vehicle
 

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A couple quick thoughts concerning your plight. First, even though visually things were not right (fluid leaks), a baseline diagnosis which included a compression test/cylinder leak down test would have identified the bad cylinder(s) prompting a different outcome & preventing what you are experiencing at this time. Is a "core shift " similar to a time warp fluctuation? Like it worked before and now that it's shifted in time it doesn't? Nonsense.

Had the compression/leak down test been performed accurately as a baseline test procedure, the 2 nearly dead holes would have been identified prior to the cylinder head exchange (exchange parts are normal in the business) which would prompt a competent mechanic to look further into the head condition
(combustion chamber leak down test to determine valve area problem) and the cylinder liner pertaining to those cylinders ( although checking all 8 would be nice) which have been prone to various failures from the early 1960's. By simply determining what the head and block condition was prior to repair you might have made a different decision concerning repair/replace. This is the only purpose for competent diagnosis, so you can make the decision without throwing parts at the problem hoping the "core shifts" back to normal.

Failed O2 sensors can cause idle misfires but so do improper spark plugs, they (spark plugs) are not "one size fits all" there is a specification that details the proper plug based upon firing voltage and saturation from the coil of specific set-ups. Use the correct plug (or tell them to).

Lastly, the most overlooked problem in dealerships and independent shops is the real fact that after a diagnosis new parts are not always "good parts" more frequently in independent shops using rebuilt or reconditioned than dealerships using new/reman parts; In this business the advantage the dealership has in parts is based upon a more complete core return inspection for remanufactured parts, parts that do not measure up to standards are generally sold to bulk rebuilders keeping these from entering the manufacturers warranty system this creating another problem stream for the independent installer as a part failure/comeback; Check new parts for function, they fail too.

Be careful of "Model Expert, Specialist, The One and Only" type shops, they are not all the same, some are truly experts in their chosen product, most are not.

Here's hoping the "core shifts" back for you and you get to enjoy your truck again. Be Safe

Doug
 

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Update on misfires after head work

Update: Stopped by the shop on the way home last night, checked out the disco, and got some new info. I misheard and therefore misrepresented one key fact on here previously (my bad - I am having shop send me all the numbers via email now)

Compression on cylinder 5 and 6 is actually *not* good.

Here are the latest developments:

-"The compression in cylinders 5 and 6 was around 50. The other ones are where they should be with a minimum of 160"
-There are NOT any metal flakes in the oil.
-After the car was warmed up, as it was cooling down we heard a very distinctive "click" or "snap". The mechanic noted he had heard this too previously when it was cooling down. I noticed this noise only happened twice - and it sounded like once on each bank. This has never happened before the service.
-This noise, combined with the update on compression again leads me to believe the issue is mechanical
-They are going to going to do a leak down test again and send me the results. Based on the above, I think they need to do it when engine is both at operating temp and cooled down

I think redtruck12 is on the right track - I am imagining a stuck exhaust valve when hot that "snaps" back into place after its cooled?

Will report back on the leak down test

I think I need to push them to redo the work with my own heads. Before the work was done, it was never mentioned to me that the machined heads would be from another vehicle. If I had known this, I would have just waited and told them to get my heads machined.

For reference, attached are what my old heads look like and the new heads from another vehicle
Any update on how you are making out with this truck?
Interested in the end resolve
 
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