HELP!!! Sudden drop in oil pressure.

HELP!!! Sudden drop in oil pressure.

Postby mack124 » Sun Aug 06, 2017 3:30 pm

Hi Everyone,

My 124 (with a 1995 engine) has just had a sudden drop in oil pressure. It would normally run just under 1/2 way (around 35)at idle and low revs and creep up to just over halfway (45) Today it is running at a max of 40 BUT, when at idle it drops to bugger all AND the light comes on. The engine does get a little rattly too so the pressure is dropping so it's not just the light, gauge or sender unit.

The oil in it is only a month old and is 15 /50, The bearings are only 35000km old.

Would an oil pump fail diagnose like this or is there anything else that'll cause it? The pump was not replaced when the engine was built but it did look to be in excellent condition.

Any help will be greatly appreciated and humbly received.
Present: Fiat 124 CC
1962 2300s Coupe
Past: 124 CC X 2 (one was 3 feet too short)
124 Sedan X 2
2300 Sedan X 2
2300s Coupe
2300 Estate
850 Coupe Series 1
850 Sport X 4? I think
850 Sedan X 3
Regata 100s
131 Supermirafiori.
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Location: Bathurst, NSW

Re: HELP!!! Sudden drop in oil pressure.

Postby Super Brava » Mon Aug 07, 2017 7:35 am

The oil pump is driven via a gear that meshes with the auxiliary shaft. It is internally splined and it is not uncommon for them to wear and slip on the oil pump splined shaft. Not saying it's your issue, but I have had to replace a couple over the years to get oil pressure back. Ross has a later version that is longer and engages more of the oil pump spline.
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With an M45 you'll all be eaton my dust.
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Re: HELP!!! Sudden drop in oil pressure.

Postby SPY124 » Mon Aug 07, 2017 9:36 am

I was thinking the same, oil pump drive gear.
If not, is it possible you've bottomed out the sump and it's pushed in towards the pick up?
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Re: HELP!!! Sudden drop in oil pressure.

Postby mack124 » Mon Aug 07, 2017 11:44 am

Thanks Spy and Super Brava,

I had a chat with Ross this morning. I'm going to drain the sump and just check that the oil pump hasn't come loose (if it has, I'll being giving my arse a bloody good kicking)
It could be an actual oil problem. I changed the head a month ago due to the one of the back water galleries corroding through and causing the gasket to fail and when I replaced the oil it was with oil that had been sitting around for a long time and on top of that it was a blend of three different oils. I really just used it to flush the system through after water got into it after the head gasket went.

I am fairly confident that there was no undue wear on the splined gear when I built the motor (I thought the water galleries were good too) but that said, I will definitely check it out.

Thanks again Guys

Gill
Present: Fiat 124 CC
1962 2300s Coupe
Past: 124 CC X 2 (one was 3 feet too short)
124 Sedan X 2
2300 Sedan X 2
2300s Coupe
2300 Estate
850 Coupe Series 1
850 Sport X 4? I think
850 Sedan X 3
Regata 100s
131 Supermirafiori.
User avatar
mack124
 
Posts: 209
Joined: Fri Apr 09, 2010 7:22 pm
Location: Bathurst, NSW

Re: HELP!!! Sudden drop in oil pressure.

Postby SPY124 » Thu Aug 10, 2017 12:08 am

it will be interesting to find out what it is, keep us updated Gill.
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Joined: Sat Feb 19, 2011 7:00 pm
Location: In my 128.

Re: HELP!!! Sudden drop in oil pressure.

Postby Silver 16 » Thu Aug 10, 2017 12:59 pm

While sump is off....i would check the bearing condition on the rod furthest away from pump or maybe the others.
Won't hurt while your their.
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Re: HELP!!! Sudden drop in oil pressure.

Postby mack124 » Thu Aug 24, 2017 6:18 pm

Problem solved...finally

This has taken too long as couldn't spend any quality time on it but here is what I found.

After letting the car to sit for a week, I drained the NOS oil including draining the oil filter. I even hand cranked the motor with the filter off to pump more oil through from the system.

I didn't remove the sump but checked through the plug hole to ensure the pump hadn't come loose. (I should have been a gynecologist) It was all good.

I checked the auxiliary drive gear was meshing the way it should. All was good.

I replaced the oil with new oil and what do you know? the oil pressure was back to normal.........or was it?

About 5 days later the light was coming on again!!!!! But it was starting to come on at higher revs. It was going out at about 1500rpm

This time however I noticed a new oil leak. It traced back to the oil light sender unit. I replace the unit with a spare and Bingo! It's fixed.

So basically the NOS oil was the initial problem but almost as soon as that was fixed, the sender unit crapped itself.

Thanks for all the input guys

Thanks 130C for the putting up with my phone calls and ultimately leading me in the right direction in regard to the possibility of the oil going off.
Present: Fiat 124 CC
1962 2300s Coupe
Past: 124 CC X 2 (one was 3 feet too short)
124 Sedan X 2
2300 Sedan X 2
2300s Coupe
2300 Estate
850 Coupe Series 1
850 Sport X 4? I think
850 Sedan X 3
Regata 100s
131 Supermirafiori.
User avatar
mack124
 
Posts: 209
Joined: Fri Apr 09, 2010 7:22 pm
Location: Bathurst, NSW


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