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Re: Problème huile suite transformation moteur en golf gti 3

Posted: 12 Aug 2026, 16:12
by Aidan
Ian the OP has the correct set up, pump to suit the engine with the T3 diesel pump pickup fitted - the issue it is draining down when stood so pump is not staying primed

Spoke to Baxter who suggests pump body isn't fully bolted to block because of the swap over, the pumps use different length bolts, 90mm on the 2E and 75mm on the JX and the installation is a hybrid so the bolt length required may be in between, but if the installation has used the longer bolts they might have bottomed out before the pump is fully tight against the block

The oil filter is effectively the vacuum holding the oil pump mostly primed and that can't fully drain down so maybe a small gap between pump and block

Simon says he grinds bolts to length, but hasn't done any sort of conversion in a while other than TDi, it maybe the JX bolts will work but don't have optimum thread engagement, without measuring stack height and available tapped thread in blind holes I don't know what length the bolts should be optimally but that 15mm difference could be the issue

and he reckons 20w/50 is too thick even if engine is tired and temps are high, 2E originally ran 10w/40

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 12 Aug 2026, 19:59
by colinthefox
Have you fitted the correct type of oil filter, similar to those fitted on CS and JX original engines? This type of filter has an anti-drainback valve to prevent dry starts. I use a Coopers Fiamm FT4790/B or Mann 940/25 .

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 12 Aug 2026, 20:01
by colinthefox
Avez-vous installé le filtre à huile adéquat, similaire à ceux montés d'origine sur les moteurs CS et JX ? Ce type de filtre est équipé d'une valve anti-retour pour éviter les démarrages à sec. J'utilise un Coopers Fiamm FT4790/B ou un Mann 940/25.

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 13 Aug 2026, 07:50
by Fort
Aidan wrote: ↑12 Aug 2026, 16:12 Ian the OP has the correct set up, pump to suit the engine with the T3 diesel pump pickup fitted - the issue it is draining down when stood so pump is not staying primed

Spoke to Baxter who suggests pump body isn't fully bolted to block because of the swap over, the pumps use different length bolts, 90mm on the 2E and 75mm on the JX and the installation is a hybrid so the bolt length required may be in between, but if the installation has used the longer bolts they might have bottomed out before the pump is fully tight against the block

The oil filter is effectively the vacuum holding the oil pump mostly primed and that can't fully drain down so maybe a small gap between pump and block

Simon says he grinds bolts to length, but hasn't done any sort of conversion in a while other than TDi, it maybe the JX bolts will work but don't have optimum thread engagement, without measuring stack height and available tapped thread in blind holes I don't know what length the bolts should be optimally but that 15mm difference could be the issue

and he reckons 20w/50 is too thick even if engine is tired and temps are high, 2E originally ran 10w/40

Thank you for the feedback. Best regards, Jean-Luc.

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 13 Aug 2026, 07:56
by Fort
colinthefox wrote: ↑12 Aug 2026, 20:01 Avez-vous installé le filtre à huile adéquat, similaire à ceux montés d'origine sur les moteurs CS et JX ? Ce type de filtre est équipé d'une valve anti-retour pour éviter les démarrages à sec. J'utilise un Coopers Fiamm FT4790/B ou un Mann 940/25.

Yes, I have an oil filter with an anti-drain back valve, and I tightened the water cooler right above it. Jean Luc

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 13 Aug 2026, 13:00
by silverbullet
Is it possible that the oil pressure relief valve has failed or has debris stuck in the valve seat, preventing it from sealing? This could allow the oil gallery to drain back into the sump when not running.

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 13 Aug 2026, 14:06
by Aidan
Ian, indeed
oprv is in the pump according to Google
I was wondering how drain down was prevented in the diesel I only really know WBX so where / if / there was one in the pump or pickup as there isn't one shown on the parts catalogue - it is in the lower, ie the T3 diesel, housing where the actual pick up pipe bolts on apparently, and not available separately

So I guess my next Q would be was the T3 diesel pump donating its bottom plate and pickup pipe new, or cleaned/tested if used, if it came from a dead engine I'd want to be able to check it out, but I'd probably buy a new one anyway, and hope it was good or the warranty at least was good

How is the oil pressure when running ? Ever had a wet test gauge on it ?

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 14 Aug 2026, 16:42
by Fort
silverbullet wrote: ↑13 Aug 2026, 13:00 Is it possible that the oil pressure relief valve has failed or has debris stuck in the valve seat, preventing it from sealing? This could allow the oil gallery to drain back into the sump when not running.

Good evening, where is this relief valve located? On top of the strainer?

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 14 Aug 2026, 17:09
by mioba
silverbullet wrote: ↑12 Aug 2026, 12:20
axeman wrote: ↑11 Aug 2026, 20:06 I have successfully completed several agg conversions, the same as the 2e engine. I have always used the agg oil pump and swaped over the pick up to the jx one to account for the angle of the engine installation. it is a bolt on bolt off job making sure the gauze is clean.

if you need a new oil pump I have at least 2 new ones on the shelf.

Neil

That's what I meant. JX has a pickup/strainer designed for the 50° sump angle.
Isn't there a sump baffle/windage plate in a JX too?


No there is no baffle in the JX but the AAZ

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 14 Aug 2026, 17:11
by mioba
Fort wrote: ↑14 Aug 2026, 16:42
silverbullet wrote: ↑13 Aug 2026, 13:00 Is it possible that the oil pressure relief valve has failed or has debris stuck in the valve seat, preventing it from sealing? This could allow the oil gallery to drain back into the sump when not running.

Good evening, where is this relief valve located? On top of the strainer?

Its part of the oil filter. Are you using a quality oil filter.

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 15 Aug 2026, 07:50
by Aidan
Fort wrote: ↑14 Aug 2026, 16:42
silverbullet wrote: ↑13 Aug 2026, 13:00 Is it possible that the oil pressure relief valve has failed or has debris stuck in the valve seat, preventing it from sealing? This could allow the oil gallery to drain back into the sump when not running.

Good evening, where is this relief valve located? On top of the strainer?

according to Google it's in the end of the pump plate where the pickup bolts onto it

Image

not available as separate part, I don't know if you can remove it

Re: Problème huile suite transformation moteur en golf gti 3

Posted: 15 Aug 2026, 11:23
by Aidan
but maybe like this now - as you can see cinched in place and not serviceable

Image

if you right click and open pic in another tab it is zoomable