Bit of a mystery this to me,hope it's O.K. to post in this forum.Had to change the head gasket on my 4ltr EBII motor in my XG ute.Used the AU head gasket as per other posted suggestions,a new set of head bolts,torqued to AU specs and fitted a new set of lash adjusters.
Engine oil,Castrol RX Super 15W/40 was changed only 300 to 350 klms ago along with a new Ryco Z9 filter.Lash adjusters "talked" merrily for a while,but soon pumped up on an initial test run.Previously before the head work,the oil pressure was around the 400kpa mark cold(idle and driving),and would idle at around the 350kpa mark when hot,and show not quite 400kpa(hot) when cruising at around 100klm/h.
Now after all the work(a real PIA,I'd like to meet the bloke who designed these engines and personally de-knacker him!),engine starts fine,but has at least 2 lash adjusters that clatter like hell till they pump up(sometimes they're noisy,sometimes they aren't),and the oil pressure has changed.At a cold start,the oil pressure gauge still reads approx 400kpa or just the needle pointer over,but when hot at idle,it now goes down to approx 200kpa.And as soon as you drive off(when hot)the pressure will either come up to the 300 or 350 kpa mark.Anyone had this happen to them,or can anyone offer some advice/experience?

Cheers,
Kevin.

Were the valve stem seals done when the head was out?

I know this probably gonna sounds a bit silly, but components have sympathetic wear, you have changed the setup and it needs to settle down.

I would look at running a slightly heavier oil OR the same oil with a Z89a ryco filter. if your changing every 5000km's the slightly smaller filter will still do its job fine, the smaller filter will increase oil pressure. when you change your filter pull your sender out and give it a good clean, it may be as simple as a bit of crud in there.

However, worst case scenario, your bottom end is on its way out, again a heavier oil can starve off the inevitable, but all good things must come to an end. loss of oil pressure is usually a direct result of increased bearing clearances, worn rings or glazed bores or combination of all these things.

Next change just try a 25w oil, if castrol is your prefered, go with it.

Hi,
The head was given a full service eg,machined,valves & seats lapped back in,and new viton stem seals fitted.While the head was off,and there was plenty of room to work,I removed the "T" fitting I have set up to run both the pressure gauge(fitted an "S PAK" dash cluster),and a warning light,cleaned all the parts,and refitted with Loctite sealant.
The engine has only just ticked over 193,500 odd k's since new(bought by me in '95),and has an oil & filter change at 5,000klm intervals.Compression is good in all cyls.,and the original bore hone marks were still visible.I have a couple of U.S. "PURALATOR" brand oil filters(same as a Motorcraft AFL-1),so I'll give one of them a go.I'll also try your suggestion of the RYCO Z89A filter as well.Then I'll just get in and drive it and see if everything settles down.
The engine runs really nice now with the Crow Hi-Torque cam,straight through metal cat,Pacemaker extractors and 2.5" straight throgh exhaust.It's really surprised me just how much hidden potential is in these 4.0 ltr motors.

Cheers,
Kevin.

Got a RYCO Z89A as per dc_todd's suggestion,and guess where it's made - BLOODY CHINA!Looks like the days of RYCO manufacturing a decent filter in Oz are long gone.Suppose they're now made to a price,not to a quality standard as in the past.From the box:

"Made in China to RYCO Specifications"

I'll still try it out and see what happens.Pays to read the small print as they say.

Cheers,
Kevin.

i dont use ryco. i use the motorcraft filter they are much beter, although there not made in australia either..

Made in china to australian standards is fine. Made in China to chinesse standards is the issue.

Use a Motorcraft, not a Ryco. See the size difference in the oil holes......Motorcraft has more flow.

 

 

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Wouldnt more flow be counter productive to this particular problem?

How ?????....the filter is after the pump and before bearings, etc....No flow = no pressure to be put upon objects requiring them.

I spose, Im just working off the 'pump is working at the same rate theory where a small hose attached to the output of the pump = higher pressure/lower volume against a wider hose = lower pressure/higher volume where all else remains the same ie revs etc

But, what if crap has slightly covered the pick-up screen......???....volume & pressure will be affected.

 

 

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A very good point cjh.I think I'll try cleaning the gauge sender unit first,and failing that,I'll try dropping the sump,and check the oil pump pick up screen.Will most definitely strip the pump down at the same time to check all clearances and the pressure relief valve & spring.The only major worry I have,is being able to get the one piece rubber sump gasket mine came with from new.Like all the other parts for an XG,they've just about all become ONR,and I believe the sump gasket has gone the same way.But I'll get Christmas over and done with first,then worry about it.

Cheers for all your ideas,
& all the best for Christmas & the New Year,
Kev.

Just a thought,if I've put in a re-profiled cam(Crow Hi-Torque given to me from a mates EBII),would the re-profiling of the cam lobes require an extra shim between the lash adjuster & the rocker arm?Got the spec sheet for the cam,but there's no mention of having to put an extra shim in the rocker arm to compensate for the re-grind.Would this possibly be a cause of my noisy lash adjuster problem?Glad to try anything.This intermittent clattering is giving me the s**t.