Sudden Low Oil Pressure

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Haffy Mark
Posts: 20
Joined: Sun May 25, 2014 3:37 am
Location: So. California USA

Sudden Low Oil Pressure

Post by Haffy Mark »

Just when I thought I was getting close to hit the trails again...a new problem.

My oil light suddenly started coming on at idle and it wasn't even hot yet. Normally, it would flicker at idle if it was hot out and I had run it at top speed for a bit but when it cooled down a bit it was fine. Now, I was just sitting a light and it came on. It goes off around the same revs as the gen light.

Any ideas?

Thanks,
Mark
Mark

1967 Swiss Army Troop Haflinger swb
1972 Swiss Army Pinzgauer 710m
Haffy Mark
Posts: 20
Joined: Sun May 25, 2014 3:37 am
Location: So. California USA

Re: Sudden Low Oil Pressure

Post by Haffy Mark »

Is it possible either the pressure relief or bypass spring broke? Or got stuck open suddenly?
Mark

1967 Swiss Army Troop Haflinger swb
1972 Swiss Army Pinzgauer 710m
Heinkeljb
Great Britain
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Location: Lewes,Southern England

Re: Sudden Low Oil Pressure

Post by Heinkeljb »

The repair manual has a section dealing with the various types of oil bypass pressure relief valves. The very first thing you need to do is identify which of the 3 types of bypass valve you have.

Having read through that section a couple of times, I know that Lurch (1973 - but 1983 engine) has a Type III oil bypass valve. This has a "mushroom type" valve and the spring is 46mm and no less than 45mm. The face of the "mushroom valve" works the same way as a cylinder head valve. There is a corresponding conical seat that is seals on.

The repair manual talks of "barrel valve" when you start looking at the causes and remedies section. The later type engines have this "mushroom valve" instead of the barrel valve.

It appears to boil down in your case to there being something ( a spec of dirt / metal filing) that has become caught in the valve sealing face. The earlier bypass valves used a ball bearing (but there are two sizes depending on which one you have, just to make life complicated). The bypass valve is (on my engine) below the oil pressure switch. This is the one near the the oil filter. Even if your oil pressure switch is next to the oil cooler, the valve is in the same cover as the filter. A look at the parts book shows the two different types on oil filter housing which in turn have the various different bypass valves in them.

There are of course other possible reasons for low oil pressure - switch could be faulty, might be worth replacing. Worn big ends can also produce low oil pressure at idle as the oil escapes too easily.

I would fit an oil pressure gauge to make sure of what is happening.
Then, I would run an oil flush as per its instructions, change the oil and oil filter and at the same time dismantle the bypass valve and clean everything you can. Put it back together and refill with oil, SAE 30 would seem a good choice as it is between the summer and winter weights. Run the engine up to operating temperature and watch the gauge and oil pressure light.

Hope you solve it with out having to do major engine work!

John
Haffy Mark
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Joined: Sun May 25, 2014 3:37 am
Location: So. California USA

Re: Sudden Low Oil Pressure

Post by Haffy Mark »

Thanks John. I do have the mushroom type. I took both of them out. They weren't seized so I hope it's just some small piece that got stuck in there. I'll clean it and reinstall tomorrow. Also, my switch is next to the cooler.

I measured the springs:
Bypass (lighter one) - 1.762 (should be between 1.770-1.809 per book)
Oil pump - 1.955 (no specs in book)

I did an oil and filter change last week so maybe something floating around got stuck. I can only hope.

Thanks again
Mark

1967 Swiss Army Troop Haflinger swb
1972 Swiss Army Pinzgauer 710m
Heinkeljb
Great Britain
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Location: Lewes,Southern England

Re: Sudden Low Oil Pressure

Post by Heinkeljb »

The repair manual also says you can "tap" the end of the mushroom valve to "seat it" on the valve seat. Be careful though as it mentions making the sealing face to wide gives rise to more "bits" getting stuck between the two faces. There are instructions on how to re-cut the face to get he correct width back if you need to.

Low oil pressure can also be caused by a faulty oil pump, so you will need to watch the oil light or get a gauge fitted to decide if you need to pull the oil pump and do some work on it.

John
Haffy Mark
Posts: 20
Joined: Sun May 25, 2014 3:37 am
Location: So. California USA

Re: Sudden Low Oil Pressure

Post by Haffy Mark »

Ok. Thanks John. Dale at HT said that they had the springs and plugers but no oil pumps, so hopefully it isn't that.

Is there any kind of screen on the pick up that could be clogged?

I think I might pick up an inexpensive test gauge on the way home to get some actual readings.

Thanks again
Mark

1967 Swiss Army Troop Haflinger swb
1972 Swiss Army Pinzgauer 710m
Haffy Mark
Posts: 20
Joined: Sun May 25, 2014 3:37 am
Location: So. California USA

Re: Sudden Low Oil Pressure

Post by Haffy Mark »

Well it turns out it was the oil pressure relief. I cleaned it out with a brush and reseated it with a few taps. Apparently it's very sensitive to bits like John said.

I haven't checked the pressure, but the light stays off at idle. I'm ordering springs and plungers anyway from Dale.

Thanks John



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Mark

1967 Swiss Army Troop Haflinger swb
1972 Swiss Army Pinzgauer 710m
Heinkeljb
Great Britain
Posts: 391
Joined: Wed Feb 27, 2013 1:09 pm
Location: Lewes,Southern England

Re: Sudden Low Oil Pressure

Post by Heinkeljb »

Your welcome.

If you don't want to plumb an oil pressure gauge all the way to the front dash, Just putting one in the engine bay would be better than none. At least you could check on the oil pressure.

I would never have known my Haflinger was over pressure without a gauge. The light was obviously off, but that doesn't tell you what is actually happening.

If you have the oil pressure switch up near the oil cooler, then I would suggest a pipe and "T" piece from there rather than than down at the oil bypass valve on the oil filter housing. There is not a lot of usable room near the distributor.
oil filter sensor adapter.jpg
oil filter sensor adapter.jpg (251.14 KiB) Viewed 7000 times
John
Haffy Mark
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Re: Sudden Low Oil Pressure

Post by Haffy Mark »

I may just do that. I sill want to know what the pressure is, especially after I replace the valve.

I sure wish I had the spin on filter too!
Mark

1967 Swiss Army Troop Haflinger swb
1972 Swiss Army Pinzgauer 710m
Heinkeljb
Great Britain
Posts: 391
Joined: Wed Feb 27, 2013 1:09 pm
Location: Lewes,Southern England

Re: Sudden Low Oil Pressure

Post by Heinkeljb »

Mark, The spin on filter is a completely housing, but as it is a bolt on item. You could replace your existing paper filter and cover unit with a later housing (if you can find one)!

The later housing allows you to fit a "sandwich" plate like in my picture that has 4 ports which you can attach things to.

In your case with the oil pressure switch up near the oil cooler and not a lot of room around that either, you could do something similar to what Gary Cole has (Can't find a picture. Will post one when found)) This could be fitted to either the oil pressure switch hole or to the by pass valve hole. With a short length of pipe to another "T" piece where you would fit the oil pressure sensor / oil pressure switch / oil temperature sensor. The biggest headache will be deciding what the various fitting need to be - there appear to be several different threads used for these things. Just remember the Haflinger is METRIC and the threads in to the engine will be METRIC rather than anything else.

John
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Garrycol
Australia
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Location: Canberra Australia

Re: Sudden Low Oil Pressure

Post by Garrycol »

John suggested I post up some pics of my oil pressure indication arrangements. I have the older style oil filter system but have three ports available for sensors.

Pic of the oil filter/senders
Image

You can see the brass four way connector in between the filter and the engine in the centre of the pic. The takeoff top the left has the plastic tube that runs to the gauge on the dash to indicate oil pressure. The top fitting is the oil pressure switch that operates the standard oil pressure light on the dash. The remaining blanked position to the right is where something else could go in like a oil temp sender. I have had the plastic tube style oil pressure sender in many vehicles for over 40 years and never had an issue - just keep the tube out of the sun (you know that yellow thing in the sky that is only visible in the UK for one day of the year) and away from hot exhausts.

The oil gauge (and voltmeter) were fitted by a previous owner. They are aircraft instruments and work well but have no night time illumination. I will replace them in due course with proper instruments. The pic shows oil pressure of 40psi after a cold start and at idle - when warm, idle is about 50psi and cruise is about 70psi.

Image

Garry
1973 Haflinger AP700
1977 Landrover FC 101
2007 Range Rover Sport TDV6
1971 Jaguar Series 3 E-Type Conv
1957 Landrover 88" Station Wagon
1957 Landrover 88"
Heinkeljb
Great Britain
Posts: 391
Joined: Wed Feb 27, 2013 1:09 pm
Location: Lewes,Southern England

Re: Sudden Low Oil Pressure

Post by Heinkeljb »

There is a modified paper element oil filter cover which has two out lets brazed in at the top (like a pair of horns) that is sold by one of the Austrian suppliers. This obviously replaces the your existing one.

I know the mounting system is different between the earlier paper element type and the later spin on filter type, but I think it might be possible to make a "pancake" type adapter to fit the earlier filter housing. From what I can see in the parts book, the difference is that the earlier one has a long bolt that "clamps" the filter cover to the filter body, whereas the later one has a screw thread in the center.

Maybe it is possible to make a "sandwich" plate one with a longer bolt that would be able to clamp it all together tightly enough to seal without leaking?

John
Haffy Mark
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Joined: Sun May 25, 2014 3:37 am
Location: So. California USA

Re: Sudden Low Oil Pressure

Post by Haffy Mark »

Thanks guys. Interesting setup. It sure would be nice to know the oil pressure. Temp too.

Garry - is that a 123 ignition you have? I was looking at those a few years ago but didn't think they made them for our motor. Can you tell me about it??

Thanks again guys!


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Mark

1967 Swiss Army Troop Haflinger swb
1972 Swiss Army Pinzgauer 710m
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Garrycol
Australia
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Location: Canberra Australia

Re: Sudden Low Oil Pressure

Post by Garrycol »

The 123 Ignition is the Fiat 500 model. It uses the dissy drive as a crankshaft sensor and the little computer inside has about 16 reprogrammed ignition maps and a wasted spark coil pack.

It is not longer in my car (I still have it) as it was setting ignition too far advanced and even on a dyno, it would not tune. About 47 degrees advanced at 4000rpm (should have been about 35 I believe) - the mechanic said there was something wrong so instead of mucking around with it, it was pulled out and a standard Haffie dissy put back in and ignition was back where it should be.

After I have sorted a few other things with the Haffie I might put it back in and see if I can make it work. It would be great if it was programmable like a MegaJolt ignition but you are stuck with the preprogrammed maps.

Cheers

garry
1973 Haflinger AP700
1977 Landrover FC 101
2007 Range Rover Sport TDV6
1971 Jaguar Series 3 E-Type Conv
1957 Landrover 88" Station Wagon
1957 Landrover 88"
Haffy Mark
Posts: 20
Joined: Sun May 25, 2014 3:37 am
Location: So. California USA

Re: Sudden Low Oil Pressure

Post by Haffy Mark »

Ok, thanks. That's unfortunate. I hope you get it sorted out. Sounds like a good idea.
Mark

1967 Swiss Army Troop Haflinger swb
1972 Swiss Army Pinzgauer 710m
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