new engine still giving me grief

[itchyfeet]

^^^ yes you are right ( I did have to check to believe it )

I had thought the top of the tappet was above but it's not.

Just when you really think you are getting to know these engines they supprise you

interesting they made the slot clip size and not just a drain hole

[CJH]

I guess that's the route back to the sump for 'spent' oil, i.e. oil that's done it's job pressurising the tappets, and also oil that's reached the rockers via the pushrod centre bore and then dribbled back down the pushrod tubes.

I did the plasticine test, with blutac actually. Not totally convincing, but the upper lip where the clip sits (the right hand side of the mould in this photo) is evidently 'fairly' square, whereas the lower lip is clearly chamfered.



I also tried a 16mm circlip, which is too small and can therefore centre itself inside any radius in the lip, and it seems to sit nice and tight against the lip.



My non-professional opinion is that a nicely fitting circlip, even if pushing against a slightly radiused lip, will be more secure than the paperclip jobby. The lifter would probably function even without any sort of clip, so preventing the clip from deforming and falling into the sump (e.g. from a poorly seated pushrod) would be the object here. I've ordered some 17mm and 18mm circlips to try them out anyway.

[itchyfeet]

I'd agree with that, in a non professional capacity ^^^

[CJH]

interesting they made the slot clip size and not just a drain hole

I had the same thought

Maybe there's just a lot of oil to clear. Or maybe these clips are only needed during assembly, so having them drop harmlessly into the sump if they fall out is best (to be clear, I don't believe that for a moment).

[itchyfeet]

some of the tappets I have seen have a semicircular slot in the top rim not sure why, seems it would make it easier to loose a clip.

[CJH]

Like these? I think they're just chips. I'd say there's a chance that these chips could be due to a badly seated pushrod. There have been plenty of cases on here where people have had trouble adjusting the pre-load because the pushrod isn't actually seated in the cup properly, but is resting on the edge. It's a good job there's a way for the chipped off material to get back to the sump....

[itchyfeet]

yes maybe you are right, some have more than one...

[123-jn]

THanks for all your opinions chaps, I think I agree that some circlips would be a better more secure method of securing the tops!! For the reader who said my oil temp was a bit high, I agree. The set up I am using is the same as on my old 1.9. THat would sit at about 85 up to 50mph and would climb to just about 100 or just over on a 70mph motorway sprint. The cooler sits on the auto gearbox and is cooled by the output air from the torque convertor. It has an 80 degrees stat inline. At present this engine is not only heating the oil more but also the water which also runs an 80 degree stat. The old engine used to send the gauge up to just on the centre line and would only rise on a very hot day , the fan hardly ever cut in. With this engine the fan cuts in frequently and the gauge runs 3-5mm above the centre. I have just had the engine running and the front end and back end up on ramps to bleed the system but not an ounce of air came out so I must assume it is bled!!!! Speaking to a mechanic friend just now he says that an engine is often likely to run hotter when refreshed with new parts for two reasons. Firstly everything is new and tight there is more friction, he says bearing faces and rings/bores take a while to hone themselves into full running order. Secondly there is more compression and thus more energy to dissipate in a recond DJ than a 30000 mile DG . He reckons it will settle down a bit in a thousand or so miles but that it will always ask more of the cooling system than a DG. Perhaps he's right!!
I will run some ducting to the oil cooler when I get a chance to make it more efficient in motion!!
As for the tappets tonight I checked all the preloads after two days stood. Number one inlet had about 1 turn of slack in it, number two exhaust had almost the whole 1.5 turns of slack, number three inlet had half a turn of slack and number 4 inlet had 1 turn. So that was a better result than last time. On start up she did tick over after a fashion, one tappet had a loud knock coming from what sounded like the centre of the engine. After 10 mins ticking over the knock had subsided to a tap and the rest were pretty quiet I had also changed the plugs to an old set regapped to 0.6 for lpg and the coil ran much cooler so perhaps my new plugs are a bit iffy (NGK BPR7ES). These hotter plugs ran better in the old 1.9 on LPG, the old set are a GM plug equivelant to BPR6ES, which have done 3000 miles in the 1.9.

[CJH]

As for the tappets tonight I checked all the preloads after two days stood. Number one inlet had about 1 turn of slack in it, number two exhaust had almost the whole 1.5 turns of slack, number three inlet had half a turn of slack and number 4 inlet had 1 turn.

So this means the 'check ball cavity' *is* draining down then.



Maybe this is indeed what happens in every case of tappet drain down, but wouldn't you expect the design to be such that the check ball seals the pressurised oil inside that cavity. Is engine oil compressible? Could the oil pressure in that cavity just be equalising (rather than draining) by seeping past the check ball, so that 1-1.5 turns of pre-load re-compresses it?

I had been assuming that that cavity stays full of oil, and that air only got in from a drained central lifter cavity once the engine turned over and the check ball opened the valve under inertia. But maybe it is the check ball cavity emptying or depressurising after all, which would suggest the check ball and spring aren't forming a good seal.

On the other hand, any air inside that cavity *would be* compressible, and I can't see how it would *ever* work its way out. Turn those diagrams above on their side and then consider how a bubble of air trapped in that cavity would ever get out past the check ball. A bit of air in there would mean that tappet would always be spongy wouldn't it? So are these tappets supposed to be assembled in a bath of oil to ensure there's no air in that end cavity?

[CJH]

Answering my own question - if engine oil was compressible then hydraulic tappets wouldn't work. So I reckon either the check ball and spring aren't sealing properly on your troublesome tappets, or there's trapped air in there already, which maybe compresses a bit during running, but which equalises during standing.

[itchyfeet]

When you set preload the tappet does not compress immeduately so your valves are open and no compression
leave it an hour or two and it bleeds down and you have compression.
This says to me the lower cavity can bleed

Going to try an endoscope tomorrow to see if you can view tappets without disassembly.

[CJH]

OK, I'm getting there. I guess air gets pounded out past the plunger (between the red and green parts in the figure above), rather than out through the check ball oil passage. Which is why it takes some miles to refill. And I guess that's also a possible way for the oil to drain down, rather than past the check ball. I knew there had to be an explanation that fitted the fact that tappets do drain down, so it must be oil leaving that cavity

So in your case, is it possible there are some poor tolerances between the plunger and the tappet body?

[123-jn]

Yes I am thinking the same thing, tolerances are obviously not so tight. I have just been reading a post about an American V8 with tappets that look identical inside to mine but with a roller on the base. The sizes look pretty compatible also. Their instructions were never to pre-fill new tappets before fitting, fit as packaged. The post said that these tappets were designed to bleed down quicker than usual and that they also pumped up much quicker than usual. Apparently in the V8 application they caused issues if they were fully pumped up before fitting and would pump up in a few seconds anyway? The preload used was 1.5 turns.
Back to my tappets when I compare the check ball spring to the other older versions they were a much weaker rougher looking spring but seemed to do the job ok when prefilling. I am noticing that there is less oil getting up to the rockers than was the case with the previous tappets but it appears far more evenly distributed. With the old engine the passenger side rockers were always flooded with oil and the drivers side was always much drier similar to both sides now.

[itchyfeet]

I am noticing that there is less oil getting up to the rockers than was the case with the previous tappets but it appears far more evenly distributed. With the old engine the passenger side rockers were always flooded with oil and the drivers side was always much drier similar to both sides now.

At a guess I'd say thats not just the tappets but the oil pressure.
Oil is fed to 1 & 2 side via the cam bearings, if those are leaky then there is much less oil pressure on that side

[itchyfeet]

I wonder if your oil has now degraded after reaching those tempeatures, maybe worth replacing more regularly.