qdude79

I've got about 30k on my rebuilt. Have to adjust the exhaust valves about every 5k (expected that at first). Done it five or six times. How long does this go on? I figured it was a break-in thing that would get less frequent with time...

snobdds

I think you left out the part of WHY are you doing this. Is is because they are loud, or you were told to, it is running bad etc. etc.

Normally I do it once a year to every 18 months. Even then they are not that far out of spec. If you have to do it every 5,000 miles then something is wrong.

qdude79

I start to notice it running rough, more tapping noise than usual, harder to fire at startup, slight drop in mpg's. Every time, it's been exhaust valves too tight. Readjust, and everything's fine.

snobdds

I would replace the lock nuts and adjusting screws, if that dosen't fix it then I would start to look at rebuilding the head.

Murakami

i'm having the same issue on mine with #4 exhaust valve. new head put on by PO supposedly around 20k ago. not sure what the problem is but may decide to pull the head and have a look.

qdude79

New EB head (as of 30k ago).

All the locknuts have still been plenty tight when I go to readjust.

Murakami

have you asked EB to see what he thinks the issue might be? are you having the same issue with all cylinders?

qdude79

I did. He thought possibly because the rocker arms weren't replaced, that they had to "settle" in. As I understood it, kinda like putting new brake pads on a grooved rotor.

I've noticed the problem on at least three, maybe all, of the exhaust valves by now (can't say for sure).

Haven't noticed anything on the intake side (haven't gapped to see), but wouldn't know what the symptoms would be. Any experiences?

flyingbrass

How much has the clearance been out each time?

Have you checked the ends of your adjusting screws to see if they are worn?

How many miles are on your rocker assembly? Did the pads look good when you installed the head and cam?

What clearances are you using?

Why haven't you checked the intake side?

qdude79

How much has the clearance been out each time? Depends on how long I wait to adjust.

Have you checked the ends of your adjusting screws to see if they are worn? Didn't know I could/should. How would I do that?

How many miles are on your rocker assembly? 180k

Did the pads look good when you installed the head and cam? I didn't. Shop did.

What clearances are you using? .12 on exhaust

Why haven't you checked the intake side? Not sure. Never had any indication they were off, but then, I don't exactly know what to look for.

fierohink

On the adjuster screws, where they hit the head of the valve stem, they would be mushroomed over a bit or just worn down. The valves are harder than the screws so the screw gives. Also look at the pad where the rocker arm rides along the cam lobe, if there has been too much valve clearence the hardness will wear on the rocker arm allowing the pad to get thin and fail. This would be evidenced by a flat spot, or if it's bad enough, a concave spot on the rocker arm pad.

FWIW I would just swap out the adjuster screws. They're like $4 each, $5 if you add a nut. So for $40 you can have all new hardware, as long as the rocker arms themselves aren't toast.

qdude79

Ok, Engnbldr recommended new adjuster screws for the rockers. Any sources for these??

flyingbrass

I don't know if aftermarket made in wherever screws are still available, but don't buy them if they are. These aren't parts to skimp on.

I got mine from 1sttoyotaparts as part of a larger order. They charge 10% of the order cost or $9.95 minimum for shipping. You might find a better deal elsewhere online for small orders, or come out about the same paying retail at a dealer. Part number is 90913-05019.

Murakami

He mentioned the valves end up getting too tight. If the adjuster screws were getting worn, wouldn't the valves become loose?

fierohink

You would think so, wouldn't you....

qdude79

Per Ted (Engnbldr):

Hi!

The adjuster screws might be the concern, those are a dealership item at the moment, we have no source.

Measure the lash at the valve tippet, .009" is a minimum for the exhaust. You might try running them a thousandth or so looser. Late ignition timing can cause the exhaust side to close up, also, it allows the head to collect heat on the exhaust side.

Ted

89redyota

i got the same problem with my 89 ive heard always do intake and exhaust dont just do one a guy whos been a mechanic for 60 years told me i listend and i aint heard nothing from them in months

fierohink

Extra bonus points if you can adjust them while the motors running


i mean

qdude79

A later response from Ted recommended using OEM screws, as the aftermarkets he tried had problems with being brittle. He switched back to OEM, no problems. Although I'm sure there's many different makes/models, I'm ordering OEM's from Texas. Probably swap 'em in within the next month.

pntbol11

iTrader: (1)

ya know... the FSM recommends checking them every 5000 miles.