View Full Version : intake cam oil tube not getting oil

05-16-2020, 07:59 PM
I recently had my sr20 rebuilt and got it installed. Oil was filled and primed and built about 25psi cranking with fuel pump turned off and CAS/coil pack harness disconnected. Got it fired up and let it run for about a minute and made 70psi oil pressure before hearing a ton of valvetrain noise so I killed it and pulled the valve cover to find that the intake cam wasn't getting any oil from the oil tube. Exhaust side is getting plenty. Luckily it doesn't look like it grooved the cam lobes as it was burning through the assembly grease before I actually shut it off.

I did pull the oil tube and blew some air through, thinking maybe it got gummed up with assembly grease but it flows air just fine. I spun the motor by hand with the bolt at the oil feed for that tube removed and got no oil, but was getting some dripping from the exhaust side tube.

One thing I did find and fix was all 4 HLAs on the intake side were bad. They were all loose so I pulled the cam, bled them and reinstalled but by the time I got everything all bolted back up I checked and they were loose again so I replaced them with some spares I had and those seem to be holding pressure.

The rebuild was basically with all new parts and bolts. I think the only things I reused was the piston oil squirters, cam oil tubes, HLAs, and oil pan baffles. Everything else including the pump, all timing chain and related components is all brand new OEM stuff.

Anyone have any ideas what might be causing this or what I can do to try to remedy it? I'm talking to the engine builder about it but just trying to get some ideas that might solve this before I have to pull the engine back out.

05-17-2020, 09:01 AM
Am I reading that right; your oil pressure was at 25 psi at cold idle when you first started it up?

I'm thinking you should be getting a lot more than that at cold idle. Somewhere in the 60-70psi neighborhood. I get around 65ish on startup on my freshly rebuilt KA (10W-40). Someone w/ an SR care to chime in?

Did you clean out the screen on the oil pickup well? possible restriction there? If you're not building adequate pressure that may explain the issue. Yeah pressure will go down to as low as 10-15 or so at idle with the motor fully warmed but the oil is hot at that point and at a lower viscosity. So you've got a higher flow for that pressure.


Sifted through a few posts there and seeing SRs showing higher cold startup oil pressure.

my oil pressure is at 80 psi on cold startup (winter) and like 60-70 (summer). then at operating temp its between 17-20

05-18-2020, 08:43 AM
Just cranking to prime the oil pump with no fuel/spark built 25psi. On actual start at idle it makes 70psi. Oil pickup was thoroughly cleaned prior to assembly.

05-19-2020, 07:07 AM
Well after studying the oil galley diagram in the FSM and poking around with a borescope comparing the passages with a spare bare head I had laying around there seems to be some kind of blockage in the oil galley that runs along the intake side just above the runners. I pulled the head and dropped it back off at the machine shop. If nothing else I learned a lot about how the oil flows in the SR which is neat I guess

05-19-2020, 08:36 AM
most assuredly...i was trying to think through what else could have happened before responding to this as its weird for only part of the system to have flow...good thing you caught it before something happened!

05-28-2020, 08:35 AM
Almost 20 years ago I tried my hand at getting an SR built.

First machine shop had some kid do work and cross threaded a cam bolt, then put a helicoil in it crooked. trashed that head

Next machine shop gave me back a block and head with so much crusty crumbly metal particles in it I had doubts about even putting it together. And immediately of course the cam oil tubes clogged and toasted the valvetrain.

next machine shop decked the head wrong or did something to the block and the head would not seal against the block properly, engine constantly leaked oil. It had other issues too but there was no way I could salvage the bad deck job so it was trash.

At the same time my friend had an SR done somewhere else and they left out the bolts that go through the oil pump caused a similar issue. That engine also had a mysterious compression issue we never solved, trashed it. I think he still has it crammed into a dark corner.

Next machine shop I'm a little fuzzy but iirc this was the third or fourth engine attempt, I forget what they did exactly but it wound up losing oil pressure after 500 miles and roasted another set of forged parts. It was either oil pickup or debris related or both.

they seem to have difficult time properly cleaning up after their work

Finally last shop, got it back and the timing chain was set incorrectly, they had bled all the oil out of the lifters (I guess on a Honda you do that?) so the valvetrain rattled like crazy and the valves would bounce on their seats causing chatter marks up every valve stem. Ruined all new valvetrain hardware.

Started doing research and its pretty hard to build an SR20 engine, look how many built and failed so fast

SRs that built and failed quick:

My learning experience is that machine shops will fuck you some way every time. Avoid at all costs. Unless you can do the work yourself, its like rolling a fixed die

These days the way I do it is, 1. decide how much power you want and what you want to do with the car, then 2. find a stock engine and transmission that will handle that power and 3. Dont ever let a machine shop near your shit

I have yet to see a rebuilt SR or KA engine with more than say 20,000 miles. Oh there are a couple out there, don't kill me. it's not impossible to do. Just super fuckin rare

05-28-2020, 09:02 AM
bad experiences

Yeah the trick is finding a TRUE machine shop that is good at their craft and not someone with a bunch of equipment they don't know how to use.

It helps to know people. Rule of thumb in my group is, if we walk into a 'machinist' to talk work and you could eat off of the floor, walk away. It seems counter intuitive but all of the machinists I have had good experiences with are so backlogged with legit work they can barely get through their shop. The guy who worked my KA shortblock is like that and my brother in law sends 2-3 sets of EJ heads through him every month (he's a mechanic that rebuilds/sells Subies on the side.)

To echo your sentiment, my buddy bought a notchtop SR back in the day. PO had blown it with an SAFCII. First machine shop bored his cylinders out of round somehow.

It's becoming harder and harder to get a good legit reference for a real machinist the way things work today. Gotta find a good local group of guys, engine make model aside, that have had actual work done or do actual work like you're looking for. I'll take real-world tangible results first-person over speculation any day. A lot of the old dudes who are masters of their craft at this don't even advertise online; they don't have to. Their customers keep them in enough work, why waste the time?

And I accept your challenge on the 20k mile built KA. at 5k now and going strong.

05-28-2020, 01:04 PM
The only thing the machine shop does for me is all the machine work, measuring and cleaning. I take those numbers, feeler gauges and ring filer and build my own engines.

Also, I only take my engines to KNOWN engine builders. My current machine shop has been in business for some 40 years, his sons are now taking over the business and one went to my University for engineering. They also build all the spec Miatas, Pro stock, 5 sec pro mods as well as 1000 HP K series engines. The only other machine shop I trust is 1.2 hours away (and worth it).

King its tough to find a proper Machine shop. Some areas more than others are just blessed with capable shops. Sorry to hear all your failure points :(
Block is holding up well so far, plus 4 additional tear downs/rebuilds for my stupidity/ignorance as this was my first built engine entirely built by myself and the FSM for all the clearance numbers (nothing blown, just dropped shims, swapped oil lines, and routine checks to make sure everything is still functioning as it should. ). Its funny, I know this particular machine shop was capable, as they took it upon themselves to look up (from Nissan direct) the factory clearance specs from the valve cover down tot the oil pan and provided said sheet after the machine work to show the specs. This provided a certain piece of mind which most shops seem to not even want to provide a spec sheet.......

I guess your YMMV

05-29-2020, 11:32 AM
even here we only have 2 that I feel could do work capably and correctly...to avoid possible issue I only gave the machine shop what they absolutely needed...bare block and pistons...then I cleaned up all items myself after getting them back...most of these places are in to much of a rush to make money instead of doing it right...

05-31-2020, 02:58 PM
I used to think building engines was difficult.

Then I rebuilt a transmission. Or rather, I tried.

I started to think that transmission were the real difficult part, the intricate and inane.

For maybe 10 years I held that point of view, and then I got back into engine building.

And it became clear that while, engines seem to have fewer parts, they are in fact more difficult to setup and build than a transmission, if for no other reason that the exploding fuel part of operation where heat and pressure turns into torque all the while trying not to wear appreciably thanks to a film of oil.

That film of oil, those spaces and the flow rate and quality of the surfaces over which oil is supposed to flow. Is microscopically influencial. Absolutely the atomic structure and it's serenity/conformity dictates weather an engine will last 1 year or 20 years, 1000 or 200,000 miles. it doesn't matter how strong the parts are because any minute wearing away of metallic debris instantly fills the engine with garbage and makes every other part practically into trash. So attention between ALL metal parts which move against those which don't... is just as important as anything else inside.

Thus the big part of whatever seems to matter is the attention to the microscopic detail and to some degree... the finesse and elegance with which the original engine layout structure/platform was designed, which help us mitigate some of labors of those micro-finish surfaces. But beyond whatever the factory supplies... you are on your own to develop new techniques and methods to just begin to discern whether what you see is really what it looks like or should look like at the microscopic level. We (enthusiasts) aren't a facility and we lack the sophisticated equipment necessary to do these things, thus we are alone as it becomes a reality of luck for many.

rood ruck