RB25 lifters bleeding off cannot solve!

[abr33]

RB25 lifters bleeding off cannot solve!

Hi guys, iv got a brain teaser for you all.

Firstly, overview. I have a built 25 in my 33 running tomei pump 2x 1.3mm restrictors etc etc. Ran 4 years problem free. many track days, lots of spirited driving and so on. Then I decided 22 pound wasnt enough so i put in 85lb supertech springs with TI retainers and camtech 272 9mm lift cams. (a 'drop in cam')

From there on I instantly had troubles with lifters. originally dropping one or 2 in and out and in no time i was losing all lifter pressure and it sounds exactly like first start up on a new set of lifters. This is all however at high RPM. Anything under 3k is perfectly fine. but one big rev and I lose all pressure and it takes about 5-10 mins idling around to recover. And i guarantee its the lifters.

Heres what iv done so far, bumped oil pressure from 65 to 85 pound. Zero change. Replaced all lifters with genuine low km ones i have spare. Zero change. Checked cam type with camtech, all good. checked spring heights, all good. Checked lifter doesn't go past the gallery. all good. 

Camtech have suggested its the vct bleeding off pressure, it cant be as its got its own feed. We have no idea what is going on. All ideas welcome! Anyone got a similar story or a fix?

[GTSBoy]

Spring pressure perhaps.  The only sensible experiment I can come up with is to try a set of not so stiff springs and see what happens.  I know there's reasons to not do that, but, you know, in the interests of science and all that.

[Scott Black]

Yet he would want the higher spring pressures to be able to increase his boost as the rb25 head with stock Springs has a tendency to get valve float much above 20psi, I'd be tempted to try the stock cams again, it probably won't help, as the issue is most likly the springs, what spring pressures does camtech recommend with there cam?

[abr33]

Thanks guys, it's the springs that came as part of the package with cams from camtech

[BoostdR]

What's the standard block to head restrictor size?

Do RB25 NEO solid lifters fit in?

[Missileman]

have you tried a heavier weight oil ?

[abr33]

I don't think neo lifters fit plus you need a different ramp on the cam for solids. 

I already have 15/50 oil can't go heavier with my setup.

I'm like the ideas but keep them coming 

[KiwiRS4T]

Have you got an oil pressure gauge? 50 oil should be more than enough - maybe there is an problem in the oil supply.

[abr33]

Yeah gauge is good mate, not using factory one. Oil supply was a thought but at idle and low rpm lifters pump back up. Which kinda breaks the supply theory 

 

[dr phil]

Maybe the new cams are letting more oil out than stock cams? They are the end of the oil pressure chain in the head aren't they?

[Missileman]

well chuck the stock cams back in, if that doesn't work try the springs.

[Dobz]

If the lifters are in good condition and cleaned then thicker oil is not the way you want to go, that's only for suspected worn lifters.

If the ramp on the cam is a bit aggressive coupled with extra spring pressure and restricted oil feeds it could explain it. You might be at the end of the lifters ability.

[abr33]

Thanks for the input guys.

Iv measured the bearing journals, they are within 0.02mm of factory cams. 

I can't really change oils as the bottoms got clearances for that thickness.

The lifters are ok, and the second set I tried have identical problems. 

I'm really thinking stuff it ill put solids in and get cams redone for solids. It's not worth pulling apart another 5 times to work it out in the meantime. I guess I was hoping someone would say 'Oh that happened to me and this was the fix' wishful right ?

[abr33]

And the reason I'm lead to look away from lifter capability is the fact these are a drop in cam and spring package 

[KiwiRS4T]

On 12/22/2016 at 9:26 PM, abr33 said:

Yeah gauge is good mate, not using factory one. Oil supply was a thought but at idle and low rpm lifters pump back up. Which kinda breaks the supply theory 

 

No the supply theory is that 2x 1.3mm restrictors are not that small and with a Tomei pump you could potentially be emptying the sump below the pick up ...are you able to log oil pressure or can you watch it while you are driving at WOT?

[abr33]

I have a warning light for oil under 30 pound. Never comes on. I can log oil but it's not connected to the haltech. However after 5 years you would think I'd have more dramas if I was running out of oil 

[abr33]

So I have updates here. 

I eventually found an oil supply problem. It was the HEL oil cooler. something in it was restrictive as hell. Lost 20 psi oil by removing it. So I bumped the pressure up. Now im running almost 100psi at 8k. So still no help on lifters. Bit the bullet and bought a set of custom kelfords. 262/272 x9.35 and my problem is gone.

I have no idea but they seem to have solved it. Now I need big lines on my cooler.

[Scott Black]

With the same Springs?

[89CAL]

Can you tell me more about the issue?
I have a HEL oil cooler kit. But the cooler itself is a Mocal. The sandwich plate is HEL (AFAIK) And thermostatic

Don’t seem to have any issues with oil but notice sometimes my lifters are a bit tickey for a few minutes

[abr33]

Sorry for the late reply guys.

So basically when I put the kelfords in I still had the lifters bleeding off. Then I started by taking off my relocation kit, no help. Then I took off the oil cooler off and my oil pressure dropped to 40 from 70. So I had a massive restriction.Luckily I have a tomie pump so I bumped it up to about 90-100 at 8k and problem gone. thinking that it was just the oil pressure I put camtechs back in. To save doing a full retune. Aaaaand it bled them all out again. So back in with the kelfords, tuned, and iv been giving it a hard time for a thousand kms and its been doing well. 

Before you rip out your oil cooler consider that I have 2.5 thou bearing clearance and 15/50 motul 300v. The thing that im lucky with is that I never spun a bearing with low bearing oil pressure.

Whilst the camtechs dont work for me, I wont take anything away from them. Malcolm has been very supportive and helpful. He is also refunding me for the cams.

Now who can recommend a cooler plate that will run -10 lines?