Oil Cooler Structural Failure

[bakerde36]

I may get blasted here but I have been using the Advanced auto Life battery that they sell for motorcycles. I have had it since Oct 2016 and still going strong. It is the autocraft and I used the LFP-4 I got it for 120 dollars with the 20% percent online discount.

[NWade]

Small update: I got the warranty replacement battery from EarthX and started the engine today. No problems cranking her up.

The new 150 psi oil-pressure sender is reporting 150psi at engine idle, even with 10-40w oil and with the airplane sitting inside a 70 degree hangar for 2 hours before starting her up. So after idling for ~15-20 seconds I shut the engine down. I checked the sender body & wire-terminal with an Ohm-meter after shutting down the engine and am getting near zero resistance (and get the same reading when using the engine block or aircraft skin as a ground)... But I'm not convinced the sender is correct. It does climb up through a range of pressures if I crank the starter with the mags & coils off; but even then it quickly jumps up over 100 psi. AFAIK the VDO senders use the same ~180 ohm range regardless of the max PSI they read, so my MGL RDAC sensor configuration _should_ be OK. The "Diagnostics" screen of my EFIS is showing some kind of value next to the Oil Pressure sender readout, but it seems way too high to be listing the raw Ohms.

I can't imagine what might be blocked or clogged that could cause such high oil pressure, and the oil cooler did not distort or rupture. I'm going to try to switch back to the 80 psi (known-good) sender and see if it maxes out as well. I'm also going to hand-rotate the prop and ensure I'm getting a good amount of oil return into the crankcase at the oil fill port (to see if I can discern whether something is choking the oil flow through the system).

As always, I'm open to thoughts and suggestions!

--Noel

[lutorm]

Small update: I got the warranty replacement battery from EarthX and started the engine today. No problems cranking her up.

The new 150 psi oil-pressure sender is reporting 150psi at engine idle, even with 10-40w oil and with the airplane sitting inside a 70 degree hangar for 2 hours before starting her up. So after idling for ~15-20 seconds I shut the engine down. I checked the sender body & wire-terminal with an Ohm-meter after shutting down the engine and am getting near zero resistance (and get the same reading when using the engine block or aircraft skin as a ground)... But I'm not convinced the sender is correct. It does climb up through a range of pressures if I crank the starter with the mags & coils off; but even then it quickly jumps up over 100 psi. AFAIK the VDO senders use the same ~180 ohm range regardless of the max PSI they read, so my MGL RDAC sensor configuration _should_ be OK. The "Diagnostics" screen of my EFIS is showing some kind of value next to the Oil Pressure sender readout, but it seems way too high to be listing the raw Ohms.

I can't imagine what might be blocked or clogged that could cause such high oil pressure, and the oil cooler did not distort or rupture. I'm going to try to switch back to the 80 psi (known-good) sender and see if it maxes out as well. I'm also going to hand-rotate the prop and ensure I'm getting a good amount of oil return into the crankcase at the oil fill port (to see if I can discern whether something is choking the oil flow through the system).

As always, I'm open to thoughts and suggestions!

--Noel

That's weird. Assuming the sensor if not totally out of whack (do you have a compressed air source you can screw it into and get a sanity check?) it seems hard to imagine getting that high pressure without blocking at least the pressure relief valve. It's supposed to open at 40 psi, I think.

Do you have one of those bypass plates you mount where the top-mounted oil cooler goes if you use a bottom-mounted one? If you replace the oil cooler with a bypass and you still have 150psi at idle then it seems the oil passages must be seriously blocked. If you have lower pressure without the cooler then it seems likely the pressure relief plunger is stuck closed and that's just the pressure it takes to push the cold oil through the cooler.

[GWMotley]

Noel,
If using an MGL extreme for example, be sure to look under the EMS setup for the type of oil pressure unit used and then the next step to check would be to verify the pressure bar setting which could be set to 2 , 5 or 10. Even if you don’t think it may have changes it is a simple check to confirm that it matches the bar rating stamped on the sender.

[pete 212]

Noel you will find the problem at the rear oil relief the piston is seeing 150+before it opens, there is a chart on here that explains the system and the cure, I would dremel a small X across the top of the piston to get the oil across the whole area of the piston which will bring the opening pressure way down, we had to do this on hydraulic cyls for the same reason, I had 250 in my system that blew 2 oil coolers 1 oil press sender and 2 oil filters, hope this helps. Pete212

[NWade]

Noel you will find the problem at the rear oil relief the piston is seeing 150+before it opens

Pete wins the prize for guessing the proper component/problem! Unfortunately he's wrong about the reason: Somehow the piston/plunger is jammed at the top of its travel.

I swear I tested this plunger for full travel in the case, before assembling the engine. However, it appears that somehow inserting it with the tension of the spring behind it has caused it to become stuck!

The darned thing will not come out, no matter how much I try to cajole it with various picks and pry-tools. I've tried gently heating the crankcase and tapping with a rubber mallet, I've read online that an M10 tap can be screwed into the underside of the plunger but an M10 appears to be too small of a diameter for my plunger... I tried removing the spring, reinstalling the plug, and cranking the starter until I saw 80+ PSI on the oil-pressure gauge. But when I removed the plug I found that the plunger still hadn't budged... Gah!

Anyone have any bright ideas? I'm thinking I might have to slowly/carefully drill a hole through the plunger and then try to use that hole to pull the thing down - but I'm worried about getting metal chips up in the engine and don't want to destroy the plunger if I can avoid it.

Thanks,

--Noel

[kevinh]

Hi Noel,

This tool will probably do it for you: https://www.ebay.com/itm/Oil-Piston-Pul ... 2749.l2649. It allows you to apply a sizable amount of pressure to grip the plunger from the inside.

[Area 51%]

CB performance sells a piston removal tool, as do most other VW parts suppliers. The part number is 6549. It's $14 plus shipping.

[lutorm]

When mine was stuck, I got it out with compressed air. However, I had to plug ALL the oil passages with wads of tissue paper before it would build up enough pressure to come out, which will be hard in your situation. You can access the side of that plunger by pulling out the freeze plug at the rear of the case, but if it's really at the top of its travel you can't get to the top. And pulling the freeze plug requires tapping for a new plug and you can't do that with the plunger in place. It would also put chips everywhere...

I guess you can try starting it, letting it idle, and watch for a sudden drop in oil pressure that indicates it's come loose. I don't know what pressure you'd have with the plunger fully out, but If you turn it off quickly I doubt there would be any adverse effects.

Edit: that tool looks like the way to go though.

[NWade]

All -

Thanks, I've already ordered the puller tool from CBP. Was curious if anyone had a different idea that was faster than waiting for the part to ship; but I guess I'll have to wait.

--Noel