3.6L Alloytec oil pressure and power issues

[RubenA]

Hey guys,

I apologise for the long post in advance! Just trying to give as much info as possible.

I've got a 2005 vz executive that has been having issues with low oil pressure and power loss.

Back story is that over a few months the engine seemed to be loosing power/torque steadily but oil pressure was fine as far as the dash was concerned.

For the past week however the oil pressure would drop as the engine warmed up. It would start fine and then gradually decrease to were a ticking noise would be audible. It seems to be worse when on an incline but happens on level ground as well it just takes longer. Not sure if these two are related but I want to get to the bottom of the oil pressure issue before it causes any more damage than it already has!

I got one of those crappy oil pressure gauges that sit in your car to see what the oil pressure was so take these readings as you will.

When idling cold it sits at 20-24psi at around 600rpm. At 2000rpm it goes to 70-74psi. It then starts to gradually drop until the gauge reads 0-4psi and the ticking is very loud. If I put the car in gear and drive a few meters it goes back up but proceds to drop all the way down again.

What confuses me is that my Gregory's says it should be 138kPa when warm at 2000rpm. 138kPa is roughly 20psi according to google so apparently I'm running that pressure at 600rpm. I'm assuming my logic is flawed at some point there as that doesn't make sense to me.

I know about the sludge problem that the alloytecs have so I'm planning to take of the sump to see if the pick up is blocked. I took the valve covers off a few weeks ago to see if anything had built up and it looked pretty good in there. Nothing but clean looking oil and some slight discolouration in the bottom left.

Any thoughts on what could cause these issues beside a blocked pick up?

Also what should I inspect when the sump has been removed? Either just for the sake of it or for damage that may have been caused.

Just stating the obvious but the engine has the correct amount of oil in it and I'm using Penrite 5w-40 Full synthetic.

Thanks in advance for any help guys.

Ruben A

 

[greenacc]

Well congrats on keeping your engine clean!
I would check oil filter first, there could be a piece of rubbish in there.
Check the pickup In the sump for blockages and metal particles from wear, then probably check the oil pump itself.

 

[RubenA]

Well congrats on keeping your engine clean!
I would check oil filter first, there could be a piece of rubbish in there.
Check the pickup In the sump for blockages and metal particles from wear, then probably check the oil pump itself.

Thanks for the reply! The cars done 160,000k's and while I've had it I've always made sure I took care of it. It hasn't skipped a beat since I've had it until I noticed the gradual power loss. So hopefully it will return to its former self very soon.

I'll be removing the sump later tonight after work so I'll let you know what I find. I'm also planning on running an oil flush Before I drain it and then filling with new oil.

How would I check the oil pump exactly? I'm assuming I might as well while I'm in there. I've read about having to prime the pump before reinstalling it?

 

[greenacc]

It's behind the timing cover, not a job for a beginner really so be careful.

 

[RubenA]

It's behind the timing cover, not a job for a beginner really so be careful.

Fair enough. I'm going to stay away from the timing cover anyway as that could introduce a whole lot of other problems.

I had a thought about the oil pump as well. If it was the oil pump wouldn't it be a consistent issue regardless of temperature/incline? Seems odd that it would be so intermittent. Then again I guess the thickness of the oil changing as it heats up could be when the pump starts having issues

 

[greenacc]

Yeah start with the easy checks before going deeper. The sump should give you a good idea what's going on. And oil filter, you don't even need to replace the filter just pull it out and have a look

 

[RubenA]

Hey,

Sorry for the delay!

I pulled the sump off and was surprised to see it was just as clean as it was under the valve covers. I had expected at least a little bit of sludge/debris!

The pick up had some small parts of what looks like rubber but it was mostly around the edges not directly in the centre of the mesh. The biggest issue seemed to be the seal for the pick up. It was squished pretty flat. I tried to compress it with my fingers to see how elastic it was. Turns out it wasn't very elastic at all as it instantly broke into pieces. I have replaced it with a new seal from Holden so hopefully that was the cause of the oil pressure problem.

I also checked the oil filter as per your suggestion and it looks fine. There were some small red particles in it but there was a total of about 5 so I didnt think anything of it.

Here are some photos of the sump and various other parts:

Pick up seal post mortem:

This is what came out of the pick up. There was a bit more but this is what I collected. Looks to have been rubber at some point in its life.

Just thought I'd take some pictures of the bottom end while I was there.

I'll let you know when I get a chance to start the car again.

Ruben

 

[greenacc]

Nice work. How difficult is it to get the sump off while engine is in the car?

 

[RubenA]

Nice work. How difficult is it to get the sump off while engine is in the car?

It wasn't TOO bad but it's not something I would choose to do in my spare time. The most frustrating part is having to drop the k-frame to get the sump out. The back of the sump drops over the k-frame to line up with the transmission housing. This section actually doesn't do anything besides look nice. It's just a hollow section in the sump casting. So not sure who's idea that was but it makes this job take a lot longer.

There is also a bolt behind the harmonic balancer which I didn't know. So the balancer had to come off as well. I didn't want to spend my life savings on the "special tool" from Holden so I ended up using a regular 3 jaw pulley removal tool. It works pretty well with a regular puller but it did take some mucking around to get it to grip because the one I have is a bit too big. I'll post the size of the puller that I have when I get home in case someone is interested.

I should be able to start the car tonight so hopefully my low oil pressure issue will be resolved!

 

[RubenA]

So I was able to finally start the car again. Everything went well! The oil pressure has doubled at idle so I believe the pickup o-ring really was the problem. It now starts at 45psi and then drops to ~40psi when it heats up but doesn't drop any lower after that. The sump isn't leaking which was by biggest concern because I didn't want to have to go through removing it again! So I'm happy about that!

For info on the pulley removal tool I used on the harmonic balancer. The one I used was a 150mm four jaw but a smaller one would have been better as I couldn't fit the jaws in the centre of the pulley. I ended up grabbing it by the inside of the outer ring if that makes sense. This isn't recommended as it could damage the pulley but in my case it turned out fine.

Thanks Greenacc for your help!