2.7 CRD Ticking, smoking - any ideas?

[Domaso]

Originally Posted by Adrian D

Oil pressure is normal, coolant temperature is normal.
Temperatures which are below that are not normal. CDI thermostats tire out pretty quickly but are cheap.

We have here 3 cases of low hot idle oil pressure. Mine is like that after a gentle drive through town but when temperature goes up to 100*C, it drops to almost zero. Another Jeep in the shop does the same and there was another one in the local Jeep Club which did the same, the guy ended up changing the rod and main bearings.

The Jeep in the shop has had the engine removed and today is bottom end inspection day, we'll see what we find.

I had some success raising the oil pressure by using the earlier mentioned "Xado" oil additive, it claims to fill-in the worn areas/scratches in the metal with some "ceramic stuff at atomic level", sounds like crap, but the bottle of that stuff cost me $140 (AUD), and it really made a difference - after ~200km my engine knock/tick disappeared completely and the oil pressure rised by one notch on a dial. I was always super sceptic about "mechanics in a can" but this time it worked for me - I guess my engine is simply pretty worn. Also, a few oil changes back I switched from 5W40 to 10W40 and that raised the oil pressure even a bit more. So I'm now pretty ok with it, having in mind that I'm driving a Jeep with almost 300,000 km engine.

[bodgie]

This is my oil pressure after a 15-20 minute drive so not quite up to temp. FWIW the oil that is in there has done 12,000km and won't be changed until it hits 15,000km.

[Adrian D]

Yup, it's not up to operating temperature.

[bodgie]

Originally Posted by Adrian D

Yup, it's not up to operating temperature.

Even so the oil pressure is pretty much the same.

I have seen it drop in the past but I changed the type of oil I use and I also have done a couple of oil flushes to clean out the crud in the engine. Once the oil flushes were done oil pressure seemed to settle down to a consistent value and it appeared to idle better, could just be the better oil though.

Jason

[Domaso]

Even looking at Jeep 2.7 CRD service manuals, I can't find the compression test procedure... Anybody with experience could help?
I'm gonna test via the glow plug holes. I've never did a test on a diesel... Do I have to disconnect fuel somehow? I mean, the HP pump is mechanically driven so it can't be switched off, so I was thinking - maybe disconnecting the line that goes from the HP pump to the fuel rail? (just routing that line to a bottle temporarily). That way, the HP pump would not draw any air and would be lubricated all the time. I don't think there is any harm if fuel rail/injectors get some air when everything is hooked back up?

Or shouldn't I touch the fuel supply at all and just leave the injectors spraying fuel into the cylinders during the test?

I've found the compression test procedure for Mercedes-Benz Sprinter 2.7 CDI (same engine), it doesn't say anything about disconnecting fuel supply...:


Compression Check: Testing and Inspection
STANDARD PROCEDURE - COMPRESSION TESTING ENGINE COMPRESSION

Maximum Compression: 29-35 bar (420-507 psi)
Minimum Comprression: 18 bar (261 psi)
Permissible Difference Between Cylinders: +/- 3 bar (44 psi)

1. Warm up engine to operating temperature (approximately 80°C, 176°F).
2. Shut off engine.
3. Remove engine cover.
4. Remove glow plugs.
5. Crank engine several times with the starter to eliminate combustion residues in the cylinders.
6. Insert compression tester adapter #8927 with check valve installed into glow plug hole of cylinder to be tested.
7. Connect compression tester hose adapter #9295 to compression gauge and test compression pressure by cranking engine with starter for at least 8 revolutions.
8. Carry out test procedure at the remaining cylinders in the same way.
9. Compare pressure readings obtained with the specified pressures. If the pressure reading is below the minimum compression pressure or if thepermissible difference between the individual cylinders is exceeded. Refer to cylinder leak down test. See: Testing and Inspection/Cylinder LeakDown Test
10. Remove compression tester and adapter from cylinder head.
11. Install glow plugs.
12. Install engine cover.

[bodgie]

I'd just disconnect the injectors so fuel doesn't get injected into the cylinders. I can't see a need to remove the fuel supply to the pump. The rail will come up to pressure as normal, and the pressure reg will relieve pressure as needed.

Just follow the MB procedure and all should be good to go.

the hardest part will be pulling the glow plugs, make sure you do this when the engine is hot, I'd also hit the plugs with some penetrating oil first to help make sure you don't have problems.

Jason

[Domaso]

Funny thing, the MB procedure doesn't even tell to unplug the injector electrical connections. I wonder why... That would surely inject some fuel to the cylinders and decrease the cylinder volume and possibly seal the rings, so it would end up like a wet test with higher readings. ...not to mention the mess of the diesel spraying through the glow plug holes...

You're probably right, the pressure regulator will divert the "overpressure" to the return line.

Pulling the glow plugs is easy - I've already done it several times, and I smeared the new plug threads with anti-seize, so - piece of cake
I haven't tinkered with the plug #5 with the fuel rail being on though... That one is going to be a major PITA...