Valve Noise?
 

I finally got my car running decently. It's been about 150 miles since the engine was out. It just started making this terrible noise when I got home today.

Rod bearings were replaced, head was rebuilt w/Datsun springs, all new gaskets, Vitesse turbo kit, oil pressure is 4 bar at warm idle, idle is more erratic, VR-1 oil level is right in the middle. It is very loud and clanky sounding (more than the video), but was completely fine before right now. It looks like it is leaking a small amount of oil from the front cam/behind distributor area I just noticed. Several drops that fell onto the timing cover.

The best I could find was possibly a lifter not getting oil and to try revving at 3,000 RPM for 5 mins, but it sounds pretty bad. It was run at 3,000RPM on the freeway home for a few minutes prior.

I let it cool down for a couple hours, though it's still warm to touch, and filled the oil. The noise is still there. Revving >2,000RPM makes the noise pretty much disappear but then it gets louder again towards 3,000 RPM. Letting up from there is very loud and clanky back to idle.

I'll mess with it more when I get home but I'm guessing since it started while warm, it's probably some debris that made its way in during deck or oil pan gasket cleaning. I'll try a quart of ATF to see if that helps and change the oil. Otherwise I'll pull the cam tower and replace with a rebuilt lifter if that's it.

It made it >100 miles without issue, so I don't think timing could be off, or something worse like bent valves, tight guides, or that guy who had a retainer come off and grenade a cylinder.

It sure sounds like a lifter. Most go away after a while, but yours may have already gone far enough to pump up.

If it were mine, I'd try a little more 3K RPM, but I don't have to wrench on yours..

5 1/2 mins at 3000 rpm didn't make it sound any better, so I guess I'll try the ATF.

You have a link to these Datsun springs...?

Who assembled the valves, springs, retainers, set height, etc...?

T

https://rennlist.com/forums/944-turbo-and-turbo-s-forum/856051-8v-valve-spring-option.html These springs

I had a head shop who said they've done it before do it and gave them the factory service manual info.

15 minutes with ATF didn't help either. It got a little deeper sounding part way through, but no quieter or better. It sounds like it's coming from cylinder 1 just standing there. With a screw driver, I think it's the intake, but they all sounded pretty similar. I guess I'll have to pull the cam tower again and see if I can find a soft one.

T,
Could it be the OPRV failed ?
Max

My oil pressure is good. It was only ~1.5 bar warm idle before I replace almost everything, including rod bearings. Now it's 4 bar. I did use the valve itself to line up the housing, but made sure it easily threaded by hand after the housing was tightened. Is that a possibility?

How do you tell the difference vs a lifter?

I was thinking more along the lines of them not fitting the factory lower spring cup, and they either twist forced the springs in them to leave them in place, or they discarded them and just left the soft shim between the spring and the head.

Big no-no either way...., but I see in the thread OP linked that Shawn said they fit the cup, no problem.

Could be the check valve/oil limiter in the head was damaged during the head work or is stuck if they bead blasted it.

Trying to remember if the cam housing gasket can go on backwards...., that would block upper oil feed.

T

You should be fine there, what year is the engine..?

T

Yeah, I just trusted the shop. They said they went in fine with no issues.

Yeah, I saw things about the gasket being able to go on backwards. I think it was obvious which side was the front, but it was over a year ago. I saw someone had to cut there's over the feed hole to keep it from being forced up, but I don't think that fixed their problem anyway. Would it last 150 miles symptom free if it was backwards? Same with the oil limiter in the head, if it was damaged/stuck would it be fine for 150 miles then fail? The lifter or oprv seem more likely to spontaneously fail.

It's an '88, so 1 piece valve.

Well, it was a lot worse than a lifter. The cam bolt was completely loose. I don't know if it can come loose easily, or I somehow forgot to torque it before putting the distributor connector in front of it. I couldn't tell before getting the timing belt off, but after that the retaining collar was wobbling. It destroyed the woodruff key slots on the camshaft and the sprocket and let the key wobble. It let the sprocket spin about 1 tooth total forwards and backwards (i.e. 1/2 tooth each direction).

I pulled the spark plugs and checked with a scope, though I couldn't see much. 1 & 4 were at the top, but I didn't see any piston damage, from what I could see, or any chunks of metal. 2 & 3 piston and part of wall I could see looked good. All spark plugs looked undamaged.

Lifters look ok, though 2 of them are soft in cylinder 2 and 3. So I'll replace those two.

Should I just replace the sprocket, retaining collar, and camshaft or replace the whole cam tower? Could the housing journal bearing have been damage - would I be able to tell? Edit: looks like others have just replaced the cam. I'll see how Lart's prices compare.

When I swap, what should I do with the lifters? Everything says not to mix them up, but when you swap cams they're all going to be completely different anyway.

Could 1 tooth of timing play cause any damage or did timing belt tension hold it place? When at TDC, the cam sprocket was dead on. Should I check or replace anything else? Pull the intake manifold and check valves? Edit: looks like others had no issue.

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