Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
Possible bent con rod with normal compression test?
326 views
Skip to first unread message
Lee
Oct 2, 2013, 2:42:17 PM10/2/13
to
Asking on behalf of someone else, is it possible to have a bent con rod
and still have normal compression readings on test? All 4 cylinders read
300psi, cold, no throttle.
Story is CR turbo diesel with shorted ecm. Might have had leaking
injector prior to this. Ecm and injectors replaced and now timing seems
off (white/grey smoke) with misfire and massive over-fuelling. Worse
when cold, is drivable when hot, though obviously down on power.
No DTC codes. Injector pulses and fuel rail pressure look ok on 'scope
Bent con rod suggested by diesel expert...
and still have normal compression readings on test? All 4 cylinders read
300psi, cold, no throttle.
Story is CR turbo diesel with shorted ecm. Might have had leaking
injector prior to this. Ecm and injectors replaced and now timing seems
off (white/grey smoke) with misfire and massive over-fuelling. Worse
when cold, is drivable when hot, though obviously down on power.
No DTC codes. Injector pulses and fuel rail pressure look ok on 'scope
Bent con rod suggested by diesel expert...
Duncan Wood
Oct 2, 2013, 5:32:10 PM10/2/13
to
Lee
Oct 2, 2013, 6:11:37 PM10/2/13
to
On 02/10/2013 22:32, Duncan Wood wrote:
> Wed, 02 Oct 2013 19:42:17 +0100, Lee <cyber...@ukonline.net> wrote:
>
>> Asking on behalf of someone else, is it possible to have a bent con
>> rod and still have normal compression readings on test? All 4
>> cylinders read 300psi, cold, no throttle.
> Wed, 02 Oct 2013 19:42:17 +0100, Lee <cyber...@ukonline.net> wrote:
>
>> Asking on behalf of someone else, is it possible to have a bent con
>> rod and still have normal compression readings on test? All 4
>> cylinders read 300psi, cold, no throttle.
> What are they supposed to read.
Was more concerned with balance, but might have answered my own
question, as book says between 350min and 450max @200rpm no fuel
Best do compression test again I think....
Lee
Dave Baker
Oct 3, 2013, 12:49:35 AM10/3/13
to
"Lee" <cyber...@ukonline.net> wrote in message
news:bb37o9...@mid.individual.net...
> Asking on behalf of someone else, is it possible to have a bent con rod
> and still have normal compression readings on test? All 4 cylinders read
> 300psi, cold, no throttle.
That's pretty low numbers for a diesel. Try again with the engine hot. A
> and still have normal compression readings on test? All 4 cylinders read
> 300psi, cold, no throttle.
leakdown test might be a better way of determining whether it's engine wear
or bent rods. I'm not sure why or how all four rods got bent though and
apparently by exactly the same amount.
--
Dave Baker
Duncan Wood
Oct 3, 2013, 5:38:18 AM10/3/13
to
Mrcheerful
Oct 3, 2013, 6:14:32 AM10/3/13
to
Lee
Oct 3, 2013, 9:37:11 AM10/3/13
to
On 03/10/2013 11:14, Mrcheerful wrote:
>> Bending all 4 seems unlikely :-) Are you sure the cam timing's right?
>
Was running perfectly before ecm shorted out, taking two injectors with
>> Bending all 4 seems unlikely :-) Are you sure the cam timing's right?
>
it. Although timing is on the list to check again.
> what engine exactly is it?
check out and it's not throwing any codes.
Rail pressure has been checked and pronounced ok.
Lee
Lee
Oct 3, 2013, 10:04:42 AM10/3/13
to
On 03/10/2013 05:49, Dave Baker wrote:
> That's pretty low numbers for a diesel. Try again with the engine hot. A
> leakdown test might be a better way of determining whether it's engine
> wear or bent rods. I'm not sure why or how all four rods got bent though
> and apparently by exactly the same amount.
It was running perfectly before the ecm blow-up though.
> That's pretty low numbers for a diesel. Try again with the engine hot. A
> leakdown test might be a better way of determining whether it's engine
> wear or bent rods. I'm not sure why or how all four rods got bent though
> and apparently by exactly the same amount.
Got to agree with you, and I'm thinking a bent rod was suggested because
there doesn't appear to be any obvious electronic or mechanical faults
anywhere else.
Lee
Lee
Oct 3, 2013, 10:12:49 AM10/3/13
to
Forgot to add, did remove injectors and checked to see if maximumm
height of each piston was the same. Which it was, as far as such a test
is useful.
Lee
height of each piston was the same. Which it was, as far as such a test
is useful.
Lee
Mrcheerful
Oct 3, 2013, 11:51:43 AM10/3/13
to
try running with the maf disconnected and see if it improves.
Tim..
Oct 4, 2013, 5:09:24 AM10/4/13
to
compression test i.e. with an amps clamp on the starter feed, and scope will
clearly show if one pot is lagging behind the other 3...
If this is a VAG car, i;ve known cam lobes to spin on the shaft, as they are
merely pressed on....
Tim..
Lee
Oct 4, 2013, 8:16:53 AM10/4/13
to
Diesel "expert" who suggested bent rod clearly wasn't so expert after all...
Just come back from having the new (not recon) injectors independently
tested, two have excessive leak back and 1 of those also has a 0.1ms
delayed injection response.
Mate has had to order another two injectors and I sense a warranty
argument looming....glad it's not me, as these are piezo injectors and
they aren't exactly cheap :(
Lee
Just come back from having the new (not recon) injectors independently
tested, two have excessive leak back and 1 of those also has a 0.1ms
delayed injection response.
Mate has had to order another two injectors and I sense a warranty
argument looming....glad it's not me, as these are piezo injectors and
they aren't exactly cheap :(
Lee
Dave Baker
Oct 4, 2013, 9:24:02 AM10/4/13
to
news:bb7ptm...@mid.individual.net...
You still have to resolve the low compression test numbers. Either it was an
invalid test because the engine was cold or there are other problems to
sort. Most engine problems aren't a single fault but a combination and it's
easy to forget one part of those when something obvious rears its head but
turns out to be a red herring.
--
Dave Baker
invalid test because the engine was cold or there are other problems to
sort. Most engine problems aren't a single fault but a combination and it's
easy to forget one part of those when something obvious rears its head but
turns out to be a red herring.
--
Dave Baker
Lee
Oct 4, 2013, 9:55:20 AM10/4/13
to
On 04/10/2013 14:24, Dave Baker wrote:
> You still have to resolve the low compression test numbers. Either it
> was an invalid test because the engine was cold or there are other
> problems to sort. Most engine problems aren't a single fault but a
> combination and it's easy to forget one part of those when something
> obvious rears its head but turns out to be a red herring.
That's a good point. I did manage to convince him to repeat the test hot
> You still have to resolve the low compression test numbers. Either it
> was an invalid test because the engine was cold or there are other
> problems to sort. Most engine problems aren't a single fault but a
> combination and it's easy to forget one part of those when something
> obvious rears its head but turns out to be a red herring.
and he got 320 psi. Mate maintains that engine was running fine before
and so is not at all concerned about the compression numbers, apart from
them being balanced.
We shall see.... :)
Lee
0 new messages