Zero compression is valve train not typically bottom end. low compression is typical of compression leaking around the rings. When you see zero there is a major leak and either valve is bent or head gasket is blown out. Do a leak down test to determine where the compression is going.
97 disco 1 SD need help
- Thread starter Disoteka
- Start date
1 and 7 plugs appear to be due to burned valves, the rest are carbon fouled. You going to need a complete valve job. How many miles?
Could be! However without more info like is it overheating, mileage, etc. But 2 dead cylinders definitely a problem.
I put a leak down tester on mine when it had a bad head gasket.. Never really needed it to test anything, as once I put compressed air into the cylinder the leak was blowing out underneath the head.
This old school method can also work to see which valves are leaking by putting at TDC, having pressure in cylinder, then listen into the intake and exhaust for hissing.
This old school method can also work to see which valves are leaking by putting at TDC, having pressure in cylinder, then listen into the intake and exhaust for hissing.
Update!
bent push rods !
I am going to do a leak down test and check the compression. This vehicle is a project and I really dont want to do a total rebuild.
Question:
if the leak down test is good you think I can get away with just replacing the rods and maybe the lifters ?
Should I replace all rods ? New or used
There are about four bent rods
bent push rods !
I am going to do a leak down test and check the compression. This vehicle is a project and I really dont want to do a total rebuild.
Question:
if the leak down test is good you think I can get away with just replacing the rods and maybe the lifters ?
Should I replace all rods ? New or used
There are about four bent rods
Attachments
Nice! Here's what I would do next, figure out why it bent. Lots of inspection.
I think you have timing chain, camshaft failure. The weakest link are pushrods. Take the front cover off and intake manifold off and do more inspection. I’m sure you will find the worn out parts.
You mentioned 4 bent pushrods were they all on the same cylinder head? On a previous post you showed spark plugs #1 with zero psi. Probably stuck lifters which bent push rods.
4 bent pushrods... How's that timing chain sprocket looking? Maybe the prior owner thought it was a rotary engine...over-rev'd it.
I am trying to visualize how stuck lifters bend pushrods... I mean, in that case the valve(s) would need to be stuck open and the *piston* would be doing the bending
Did you run another compression check with the bent rods pulled?
*I would pull and check all the pushrods.. but since you've gone this far, I'd probably replace them (and the lifters).
I am trying to visualize how stuck lifters bend pushrods... I mean, in that case the valve(s) would need to be stuck open and the *piston* would be doing the bending
Did you run another compression check with the bent rods pulled?
*I would pull and check all the pushrods.. but since you've gone this far, I'd probably replace them (and the lifters).
The inside of the heads look fairly clean. That may well be a good sign the engine has good life left in it.
Were you given any history on why it was parked? Maybe, as was suggested, it was over revved. If that is the case you might be lucky enough to get away with replacing push rods. You are going to need push rods no matter what. If you want to take the minimalist approach get some new/used push rods, drop them in, put the rocker shafts back in, check the engine timing by turning it by hand and make sure it doesn’t meet interference. If it doesn’t meet interference and the engine timing seems correct, do a compression test. If it improves at all, see how it runs.
If it meets interference when turning by hand and or the engine timing is off, (or if you don’t want to be a minimalist) pull the heads and timing cover and do full inspection.
My rule of thumb is always take the minimalist approach assuming the best and work from there.
If you want to spend as little as possible during diagnosis, I might have some used push rods I can send your way.
EDIT - I somehow missed you had zero compression on 2 cylinders. Im sure you have the same thought but I suspect you have bent valves. Check the compression with the push rods out. I really doubt it will be better. You don’t even need to put a gauge on it. Just rotate it by hand to see if it has any compression. Ive replaced individual valves on heads and put the heads right back on after correcting what caused them to bend with good success. Make sure the heads are flat off course.
Were you given any history on why it was parked? Maybe, as was suggested, it was over revved. If that is the case you might be lucky enough to get away with replacing push rods. You are going to need push rods no matter what. If you want to take the minimalist approach get some new/used push rods, drop them in, put the rocker shafts back in, check the engine timing by turning it by hand and make sure it doesn’t meet interference. If it doesn’t meet interference and the engine timing seems correct, do a compression test. If it improves at all, see how it runs.
If it meets interference when turning by hand and or the engine timing is off, (or if you don’t want to be a minimalist) pull the heads and timing cover and do full inspection.
My rule of thumb is always take the minimalist approach assuming the best and work from there.
If you want to spend as little as possible during diagnosis, I might have some used push rods I can send your way.
EDIT - I somehow missed you had zero compression on 2 cylinders. Im sure you have the same thought but I suspect you have bent valves. Check the compression with the push rods out. I really doubt it will be better. You don’t even need to put a gauge on it. Just rotate it by hand to see if it has any compression. Ive replaced individual valves on heads and put the heads right back on after correcting what caused them to bend with good success. Make sure the heads are flat off course.
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“But other than that I cleaned the MAF and it still shows 0%.”
In my case my diagnostic tool wasn’t reading correctly, it also showed 0.0. It is a newer Autel. My 25 year old one read correctly. Speaking from personal experience, unplugging the MAF can tell you a lot. I had a vacuum leak and unplugging it made it run very smooth.
In my case my diagnostic tool wasn’t reading correctly, it also showed 0.0. It is a newer Autel. My 25 year old one read correctly. Speaking from personal experience, unplugging the MAF can tell you a lot. I had a vacuum leak and unplugging it made it run very smooth.
Why look at the reluctor ring. If you have spark it’s good. If it’s not running I would expect 0% MAF on an engine that won’t run.
With what you say you have and don’t have it seems like one of 3 things. The injectors are not getting opened, the engine has no compression, or the fuel is so shitty it won’t burn.
Just to make sure, you've checked the hall effect (crank) sensor? I mean, after the pushrods repair... Also, you inspected the time chain/gear set?