jhnbrns wrote:
The idle sound fine to me however the revving up from park sound different. Whining or whirring. When driving under 20mph, the vehicle accelerates just fine. Try to accelerate up to 30-50, there is a loss of power, lots of little metallic knocks and dark smoke on the road. The gears shift fine and I can gently get up to 60 mph. While cruising at 60, theres very little smoke.
Timing belt and t-stat were replaced last June. The problem became obvious in November. I'm still not ruling out a timing issue. I've already replaced both CAC hoses(small crack at turbo,snorkel), replaced turbo intake snorkel (deteriorated at turbo, replaced both vacuum controls(no known issues), replaced MAP sensor(did have P0105 once and it was clogged), replaced lower EGR tube(leak to EGR, used RTV to seal), high temp RTV on the flange of the upper tube at the EGR(has a .125" split at the flange, observed smoke when rev'd). The RTV is holding fine on upper tube. I pulled the throttle and intake elbow and cleaned (elbow had at most .25" build-up at the bend, throttle had a little gunk on one quarter side of the valve).
What do you think?
Timing is fine since idle is smooth and no different.
Turbo is fine since spins freely with very little play, and variable vane actuator moves with vacuum change.
EGR is working since I could observe black smoke through the EGR leaks above idle. Fixed.
Sensors are fine with no codes.
Air intake is fine. Small leaks repaired. Was not blocked.
Significant loss of power all the time not caused by small coolant leak (read earlier post).
I would like to know how to check/diagnose the timing advance. Or what can negatively affect the timing under load. Thanks.
Thanks
There isn't a "timing advance" to be able to check on these - this isn't a Chevy 350 or a Ford 302. Slightly different setup here, the timing is fixed and the computer directly controls the injection events. Diesels need to run lean, and as much as 250:1 is normal at idle. Running richer than optimal leads to higher cylinder temperatures which (on this engine) can be a contributing factor to valve separation. The usual result of running rich is smoke (wasted fuel) and the cure is reducing fueling or increasing air charge. Since you are not controlling the fueling, then the air charge must be getting reduced somewhere from what the computer "thinks" the air charge is.
The usual way this happens is one of three things:
Boost leak directly to air - heard as whooshing noise, can be loud and higher pitched.
Boost leak to exhaust through the EGR valve - the EGR is a VERY poor design and even when functioning, may not seal effectively when closed.
Exhaust leak to air - This results in reduced boost pressure because exhaust directly powers the turbo, and if the heat of expanding exhaust can escape from (usually) a cracked EGR pipe, then there will be much lower boost, lots more smoke, and soot covering EVERYTHING in the back of the engine bay and the firewall area.
RTV is a nice idea, but doesn't hold up against the temperatures or the pressures of the exhaust system. We are talking 1200 degrees easily and many hundreds of PSI.
If you are having a coolant leak, you likely also have the typical head bolt weakening, and ARP studs are the solution to that particular problem. The amount you are losing sounds very typical, but if that has been happening for over a year, you may want to think about replacing the head gasket entirely at this stage. There is a very good chance that the leaves of the gasket have rust between them by now, and simply installing the studs may not cure the problem.
Doing a refresh on the top of the engine is one of the services that I offer, and have many satisfied customers, if you are not equipped to handle the labor yourself. The timing system needs to be disassembled to do this work, but luckily the labor for all of this overlaps and the EGR delete is part of the process. I do think your engine is a good candidate for many more happy miles, what you are describing just sounds like the typical problems that all tend to collect around this point of mileage.
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