Jetta MK3 Oil pressure puzzle.

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MaverickMe
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Jetta MK3 Oil pressure puzzle.

Post by MaverickMe »

Hi, new to the forum but have used a lot of the great advice & tips from here before. Thanks to all! Firstly, let me state that I am mechanically "challenged" but a keen "give it a bash" type person and this has probably got me into my dilemma. Secondly, please excuse my longish post:

One morning I started my '95 Jetta MK3 1.8 CLX and it sounded "noisy" at the top of the engine. I was advised that the oil pump was packing up and should be replaced ASAP.

I then bought and replaced the oil pump, sump gasket, oil filter and oil. Upon starting the oil light on the dash was flashing. From this forum I quickly realised that I had not primed the oil pump so I then redid the entire process using the same spares but this time primed the pump by splitting it and packing it with grease (A tip from mechanic).

On starting the oil light and noise were gone, I then used an external pressure gauge to test the oil pressure which was 3.5 bar (on the filter) at idle and rising to over 6 bar when revved slightly. I then took her for a drive and 2 km later the oil light came on along with a buzzer. On the off-chance it was a dodgy pressure sensor I replaced both, still no oil pressure but no buzzer now and the noise was back.

I retested the oil pressure using the external gauge at the oil filter and head oil sensors and it was back to zero. Any suggestions as to what I have done wrong or what I could have missed? Any advice would be greatly appreciated. My thanks in advance.
'95 VW Jetta III 1.8 CLX
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marzbars
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Re: Jetta MK3 Oil pressure puzzle.

Post by marzbars »

Look at the oil sensor on the oil filter
MaverickMe
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Re: Jetta MK3 Oil pressure puzzle.

Post by MaverickMe »

Hi Marzbars, thanks for the reply. I have replaced both sensors, head and filter, and the situation still remains the same sadly.
'95 VW Jetta III 1.8 CLX
Howie-WP
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Re: Jetta MK3 Oil pressure puzzle.

Post by Howie-WP »

MaverickMe wrote: Sat Jun 11, 2022 10:28 am Hi, new to the forum but have used a lot of the great advice & tips from here before. Thanks to all! Firstly, let me state that I am mechanically "challenged" but a keen "give it a bash" type person and this has probably got me into my dilemma. Secondly, please excuse my longish post:

One morning I started my '95 Jetta MK3 1.8 CLX and it sounded "noisy" at the top of the engine. I was advised that the oil pump was packing up and should be replaced ASAP.

I then bought and replaced the oil pump, sump gasket, oil filter and oil. Upon starting the oil light on the dash was flashing. From this forum I quickly realised that I had not primed the oil pump so I then redid the entire process using the same spares but this time primed the pump by splitting it and packing it with grease (A tip from mechanic).

On starting the oil light and noise were gone, I then used an external pressure gauge to test the oil pressure which was 3.5 bar (on the filter) at idle and rising to over 6 bar when revved slightly. I then took her for a drive and 2 km later the oil light came on along with a buzzer. On the off-chance it was a dodgy pressure sensor I replaced both, still no oil pressure but no buzzer now and the noise was back.

I retested the oil pressure using the external gauge at the oil filter and head oil sensors and it was back to zero. Any suggestions as to what I have done wrong or what I could have missed? Any advice would be greatly appreciated. My thanks in advance.
Is this the correct way of "priming" the pump? Surely grease will block it? Should you not use oil to prime it?
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Re: Jetta MK3 Oil pressure puzzle.

Post by MaverickMe »

Hi Howie-WP, according to the VW mechanic one can use either method however grease is quicker/easier/"cleaner" according to him. I have since removed the new oil pump for the 2nd time and there is only a small residue of any grease left, all the chambers are clear and clean yet still zero oil pressure.
'95 VW Jetta III 1.8 CLX
Howie-WP
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Re: Jetta MK3 Oil pressure puzzle.

Post by Howie-WP »

MaverickMe wrote: Mon Jun 13, 2022 3:40 pm Hi Howie-WP, according to the VW mechanic one can use either method however grease is quicker/easier/"cleaner" according to him. I have since removed the new oil pump for the 2nd time and there is only a small residue of any grease left, all the chambers are clear and clean yet still zero oil pressure.
Maybe the missing "grease" is now blocking the oil passage ways? Grease is less liquid than oil...... I'd check for residue close to the passage ways near the sensors and see......
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Re: Jetta MK3 Oil pressure puzzle.

Post by EX-DOHCTOR »

Ordinarily clean fresh motor oil should be used to prime the pump. Not sure why you would want to introduce grease to the oil system.

Unless the idea is that the grease melts into solution in the oil when the engine heats up?
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Re: Jetta MK3 Oil pressure puzzle.

Post by Howie-WP »

EX-DOHCTOR wrote: Mon Jun 13, 2022 4:38 pm Ordinarily clean fresh motor oil should be used to prime the pump. Not sure why you would want to introduce grease to the oil system.

Unless the idea is that the grease melts into solution in the oil when the engine heats up?
Agreed, sounds like BS. You are basically contaminating fresh oil. Oil <> grease .... If I was OP, I'd flush engine and try again, without the grease move....
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Re: Jetta MK3 Oil pressure puzzle.

Post by MaverickMe »

EX-DOHCTOR wrote: Mon Jun 13, 2022 4:38 pm ....Unless the idea is that the grease melts into solution in the oil when the engine heats up?
Hi DOHCTOR, I also questioned this method and as you say the grease melts into the oil and the minute quantity has zero effect on the oil.
Last edited by MaverickMe on Tue Jun 14, 2022 4:35 pm, edited 1 time in total.
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Re: Jetta MK3 Oil pressure puzzle.

Post by EX-DOHCTOR »

Just as a matter of interest, what grease did you use?
2014 - VW Jetta 6 - 1.6 TDi DSG
2000 - VW Golf 3.5 Cabrio - 2.0
1980 - VW MK1 GT - 1.8 Carb - https://www.vwclub.co.za/forum/viewtopi ... 1&t=153861
1971 - Mitsubishi Colt 1100F - https://www.vwclub.co.za/forum/viewtopi ... 1&t=220503
MK1 Build Register: https://www.vwclub.co.za/forum/viewtopi ... 1&t=192835
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Racing is meant for the RACE track - deal with it...
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Re: Jetta MK3 Oil pressure puzzle.

Post by Howie-WP »

MaverickMe wrote: Tue Jun 14, 2022 6:57 am Hi DOCHTOR, I also questioned this method and as you say the grease melts into the oil and the minute quantity has zero effect on the oil.
Until this "melting" happens, it can block passage ways. Sounds like a BS idea; you are also mixing oils used for different jobs. But I don't really know and would not do this.....
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Re: Jetta MK3 Oil pressure puzzle.

Post by Jetta2 »

It could well be some of the grease used has blocked the oil pump pressure reliefe valve in the open position, thereby dumping most of the oil pressure back into the sump instead of through the motor like it's supposed to do.
Seen it happen on two VW motors where the grease method was used.

Just prime the pump with normal engine oil, not grease. I have never had any issues with new oil pumps when priming with oil, I will never in a million years use grease to prime a new oil pump.
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Re: Jetta MK3 Oil pressure puzzle.

Post by leeban »

@MaverickMe Please update as you go along, interested to see what the issue was/is
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