Valve adjustment diagnosis

[bretski]

It's high summer here in Colorado, so Klaus has been my daily driver for the last month or two. Last week, out of the blue, I started experiencing cold-start problems. It's been a while since the last tune-up, so I braved the heat, and started with a valve adjustment (I have hydraulics). #1, #2, and #3 were spot on. Got to #4, and had the following:
4I: 1
4E: 1.5

Horrible thoughts of valve seat recession started racing through my mind. Pulled out my notebook to compare to my last valve adjustment (done about 3000 miles ago):
1E: 0
1I: 0
2I: 0
2E: 0
3E: .25
3I: 1.5
4I: 1.5
4E: 1

So, #3 is holding steady, but #4 is worse...unless, of course, I screwed up during my last adjustment of #4. I can be scatter-brained sometimes, but I'm pretty thorough when it comes to valve adjustments.

Is it time to assume the worst, and think about pulling the engine and 3/4 head? The temperature was creeping up into triple-digits by 11am this morning, so I didn't do the rest of my tune-up routine; just the valves. For what it's worth, after the valve adjustment, the engine turned over immediately...the cold-start issue disappeared.

Thoughts?

[Hippie]

I'd keep and eye on it and look for a trend.

[bretski]

I'd keep and eye on it and look for a trend.

I'm with you, Hippie...but when does it become a trend? Three adjustments with the same 1+ turn change? Four?

[Hippie]

I'm with you, Hippie...but when does it become a trend?

For me? Gut. I just know its getting f-ed up after I have the same clearances sort of go away a few times in a row.
You'll probably just know they are sinking. Do shorter adjustment intervals for now.

[dtrumbo]

Since you mentioned cold-start and heat together. Is it possible the ambient temp is so high that the thermo-time switch isn't closing therefore your cold start valve isn't giving you the squirt you need? Sorry to muddy the waters with the whole valve adjustment thing, but that was a thought that popped into my head.

[bretski]

Not at all, Dick. A cold start in July is 65-75*. So, "cold" is relative. The very first thing to pop into my head when this started was the CSV. I've been driving Klaus to work over the last couple of weeks, and it's been 90-104* in the afternoon when I'm ready to head home from the office, and it's still taken a significant amount of cranking/throttle feather to get the engine to turn over (after sitting in the office parking lot all day). The fact that the engine started *instantaneously* today after the valve adjustment leads me away from the CSV. I will take the time to test it anyway...'cause...well...I'm anal, and have learned over 18 years that the L-Jet can be a fickle beeyotch.

When this problem arose a week or two ago, my conservative-minded self said, "Start with the basics, Bret. You haven't done a full tune in a few thousand miles, so do that first." Subsequently, #4 is making me nervous. I still need to complete the rest of the tune, plus I'm due for an oil change and fuel filter change. I'll do another valve check in October or so, and look for further trending. I'm gonna be *pissed* if I have a valve-seat issue, either way.

[dtrumbo]

...that the L-Jet can be a fickle beeyotch.

Truer words have never been spoken!

Help me out on your numbers posted above. I too have hydraulics and I turn them in 1.5 turns from zero lash. Do your #4 numbers mean that you had to turn them out an additional 1 and 1.5 turns respectively to get them back to 'zero'?

[bretski]

I too have hydraulics and I turn them in 1.5 turns from zero lash. Do your #4 numbers mean that you had to turn them out an additional 1 and 1.5 turns respectively to get them back to 'zero'?

Correct!

[Amskeptic]

I too have hydraulics and I turn them in 1.5 turns from zero lash. Do your #4 numbers mean that you had to turn them out an additional 1 and 1.5 turns respectively to get them back to 'zero'?

Correct!

Fickle L-Jet? Hmmph.
What is FICKLE are stupid vacuum hoses splitting surrepticiously, or a dipstick not fully seated.

Hard starts later in the day are not going to be the cold start valve. It only squirts to about 55* ambient in the early L-Jets, maybe closer to 80* with the later 78 + L-Jets.

In hot spells, your hard starts are more likely caused by fuel vaporizing on a hot engine, engine cools down, fuel condenses but rail is now dry. This is caused by check valves in the pump and regulator not holding pressure as long as they used to. Read your owners manual. It says in hot conditions to slowly press accelerator to floor while cranking. See if that helps.

Valve adjustment situation, I have never seen a valve that required a whole additional turn or turn and a half within one adjustment! That almost (hopefully) suggests a math error at last adjustment. Do you see that the adjustment screw threads are definitely sticking out further than the others (recession)? Do keep an eye on things.
ColinInSacramento

(p.s. if you have breaker points, go clean and gap them, check dwell to 45-50* - hard start city if gap has closed)

[bretski]

Valve adjustment situation, I have never seen a valve that required a whole additional turn or turn and a half within one adjustment! That almost (hopefully) suggests a math error at last adjustment. Do you see that the adjustment screw threads are definitely sticking out further than the others (recession)? Do keep an eye on things.

The more I mull it over, the more I think that I made an error. Both the intake and exhaust 1.5 turns off? Seems like too much of a coincidence. Maybe I turned them in, got distracted, and went back under and turned them 1.5 more. The screw heads didn't seem to be sticking out noticeably further. I do remember noting that the adjustment screws on #4 were "tighter", but that could have been a function of them running up against the nuts.

I didn't drive the car yesterday, but just went out to try starting it. Engine turned right over. I don't use points; I have a Pertronix that has been installed for many years. This weekend, I'll finish the tune-up, and see what happens.

Damn my C.R.S.!