slow oil pressure rise on 8v TC Lancia Montecarlo

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davelarcs
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Joined: April 20th, 2012, 1:41 pm

slow oil pressure rise on 8v TC Lancia Montecarlo

Post by davelarcs »

Hi Guy.

The oil pressure on my 8v Monte engine has started to be slow to rise on first start up, it takes about 7 seconds for the light to go out & the pressure gaude to read. When running the pressure is at 40-50 lbs.

It seems to me that the oilways are running back into the sump, and on first start, the pressure is low untill they have refilled.

Is my diagnosis correct? If so what can be causing this, I can't see any kind of check valve in the circuits?

Your help as usual is very much apreciated.

Thanks

Dave.
Guy Croft
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Re: slow oil pressure rise on 8c tc

Post by Guy Croft »

nope - that is due to worn bearings and/or crank, almost certainly.

G
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davelarcs
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Re: slow oil pressure rise on 8c tc

Post by davelarcs »

Oh, that is not good news :-(.

When warm & idling the oil pressure is good, not dropping out or light coming on, also the engine sounds as sweet as a nut, no rumblings or knocks, also this has come on suddenly, not developed over time, which is what I woulkd expect to see with worn bearings. Not that I'm doubting your infinetly greater knowledge than mine, I'm probably in denial.

If I have to take this engine out again, I'm going to need psycological assistance!!

thank you, Dave.
Guy Croft
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Re: slow oil pressure rise on 8c tc

Post by Guy Croft »

Dunno if you are in denial!

I will emphasise that my observation is based on your statement that:

"The oil pressure on my 8v Monte engine has started to be slow to rise on first start up, it takes about 7 seconds for the light to go out & the pressure gaude to read. When running the pressure is at 40-50 lbs.."

1. So it has (just?) 'started' - whereas it was OK before. That is a sign that something is amiss.
2. The oil pressure light should extinguish instantly cranking with the starter motor when the engine is cold. When he engine is hot it will take longer on the starter only if the engine does not fire. If the engine fires readily the light will go out almost immediately.

The bearings and crank etc do not 'drain down' after switch-off to the extent that they would affect this. Not unless you leave it for months anyway. The oil layer stays there and seals against ingress of air that would stop it priming.

I guess you could have changed the oil recently and forgotten to use a filter with an anti-syphon valve? If the oil is draining back to the pump it would add to the time to prime the system and extinguish the red light.

Has the engine just had a rebuild? You didn't grind the crank did you?

G
Guy Croft, owner
davelarcs
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Joined: April 20th, 2012, 1:41 pm

Post by davelarcs »

Hi Guy, thanks for your promt replies, I appreciate you're a busy man.

I did rebiuld the engine 6yrs ago, using your book as a guide, but have only done approx 2000miles since.

I did not regrind the crank, but did fit new main & big end bearings, allthough the existing ones looked fine, and the crank was clean.

You mention an anti syphon valve in the filter, is it possible this has stuck/sticking?

As it happens when I started the car just now, the pressure light went out straight away & the pressure rose as it should!!

I havent done anything to it yet as I wanted your view first.

thank you, Dave.
Guy Croft
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Re: slow oil pressure rise on 8v TC Lancia Montecarlo

Post by Guy Croft »

No they never stick.

Maybe your 'problem' doesn't actually exist, so-to-speak!

All too often the problem is the instruments...

G
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davelarcs
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Re: slow oil pressure rise on 8v TC Lancia Montecarlo

Post by davelarcs »

I hope so, thanks again.
WhizzMan
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Re: slow oil pressure rise on 8v TC Lancia Montecarlo

Post by WhizzMan »

Guy Croft wrote:No they never stick.

Maybe your 'problem' doesn't actually exist, so-to-speak!

All too often the problem is the instruments...

G
I've heard of quite a few examples of bad quality oil filters that have bad return valves in them. I feel it could be worth it to investigate that possibility if this problem comes back. Maybe just checking the brand and type to make sure they are up to standards right now could shed some light on the odds what is causing this?
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Urbancamo
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Re: slow oil pressure rise on 8v TC Lancia Montecarlo

Post by Urbancamo »

I have seen this happening many many times.

When I buy this X-branded filter, it has an anti-syphon valve. Datasheet also says it has that valve. But it doesn't work properly. It doesn't work if filter is positioned vertically nor horizontally.
One night and it takes 3-5 seconds to build up pressure. I've sent email to manufacturer but they don't really care. Nice.

When I change the filter to Y-brand wich I know is working, light comes off before engine is even started and oil pressure gauge jumps to position.

I once encountered a serius problem. Changed oil to certain car and started her up. It usually takes 3-7 seconds after oil change to build up pressure. 10 seconds went. Light shines. Raised the rpm a bit. Light still shines.
Turned the ignition off and went to coffee. After a break, still same. It doesnt rise pressure anymore. You could hear also there was no pressure.

I removed the filter and it was almost completely dry. Throwed it to a bin, went to parts store and bought another brand.
Then it gained pressure immeadiately. Cause of this? I don't know. I should have dissassembled the filter.

All I can say that these things just happen occasionally. This is why I use only certain brands and models wich never had failed me.
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Guy Croft
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Re: slow oil pressure rise on 8v TC Lancia Montecarlo

Post by Guy Croft »

Is there a filter brand you would depend on then?

GC
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Urbancamo
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Re: slow oil pressure rise on 8v TC Lancia Montecarlo

Post by Urbancamo »

Well there are couple brands I'm comfortable using.

- Mann
- Fiaam
- Bosch
- Filtron
- WIX

But of course I can only speak for my self based on my own experience. And of course regular users abilities to estimate filter "goodness" are very limited. And this includes me too. If you buy "name"-filters from big, quality manufacturers, you can't really go wrong.
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Brit01
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Re: slow oil pressure rise on 8v TC Lancia Montecarlo

Post by Brit01 »

Been happy with using Mann recently.
I choose the ones made in Germany (Brazilian and Chinese available) just the casing feels heavier when you pick them up. Double non-return valves, 2.2 or so bypass valve pressure.
W719/14 in my case.

Wix I heard are good but not available here. I'd like to try them.
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