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18V Engine Issue [Thinking Out Loud]

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tony barnhill

tony barnhill

Great Pumpkin - R.I.P
Offline
18V engine w/121,000 original miles - only 1 driver (me!) since day one - engine never opened but well maintained, never any problems - normal good, high oil pressure....

Running super, then wrrrrrrrrrr...lost all power & barely limped home.

Rocker had jumped off push rod...put it back on & adjusted valves & wrrrrrrrrrrr...lost power

Same rocker jumped off push rod...changed complete rocker assembly with a good, used one off shelf & changed the errant push rod....

Great power, then wrrrrrrrrrrrrrrr...no power & barely limped home.

Same rocker had jumped off push rod!

Now, I know that probably means tappet or cam problems...it could just be a tappet sticking or could be a bad cam lobe....way back when - under warranty - the dealer replaced the single chain assembly with a dual chain setup; it might be a problem but I doubt it is; there doesn't appear to be timing issues....it only happens under load; at idle everything is fine!

Tappet or cam, gotta be! DARN!!

I know what to do but I really don't want to do it!

I could pull the intake/exhaust & side cover & remove the offending tappet for examination...

Then, I could remove the radiator, distributor & front cover & timing chain (& slide the cam out for a visual inspection...

But, 120,000 miles? Is it worth it? Or should I just bite the bullet & yank the engine/transmission & do a complete rebuild?

She's back in the garage, cover is over her, oil's fine & she's now officially tucked away for the Winter; I've gotta finish the '63 Midget for the "50th..." show in Missouri before I take on anything else major.....DARN!!
 
Valve stickin' in the guide, morelike. If it produced good power when the thing's in place the cam is likely okay.
 
DrEntropy said:
Valve stickin' in the guide, morelike. If it produced good power when the thing's in place the cam is likely okay.
Click to expand...
Never thought about that, Doc....

Now, hmmmmm, how can I check that without pulling the head?
 
BFH!!! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

...just beware of flyin' collets! /bcforum/images/%%GRAEMLIN_URL%%/jester.gif
 
DrEntropy said:
BFH!!! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif
Click to expand...
Yep, exactly what I thought....remove rocker assembly, rotate engine until that piston is way down in the cylinder & WHAM a couple of times...

Put it all back together & see how she performs...

If I have to open anything up, this puppy dog's coming out for a full rebuild! But I'm not touching anything until I calm down...breathe....breathe....
 
"OOOooooommmmmmmm...."

/bcforum/images/%%GRAEMLIN_URL%%/wink.gif
 
Use a piece of wood twixt stem 'n hammer or a soft deadblow. Maybe drizzle some Marvel down the valve stem before you "work" it, add some to the crankcase and run it thru a few hot/cold cycles. No high RPM revs, just get it thoroughly up to normal temp.
 
Its under its cover - out of sight....
 
My guess would be a cam lobe, you could always check lift on the offending valve by setting up a magnetic base with dial indicator on the retainer, turn the engine over by hand and see what the valve lifts. I know, I know, you're going to tell me you don't have fancy tools like that, well since you're building your 1098, no time like the present to get one, you can get a cheapie at HF, plus you're going to need one when you start degreeing your cam on the 1098 and the GT race car. So no more exuses big boy, go get yourself a magnetic base and dial indicator /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

If the valve was stuck, it's a good possiblity it would bend the pushrod.
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]If the valve was stuck, it's a good possiblity it would bend the pushrod.[/QUOTE]
HUH!! Just looked - pushrod I took out has a tiny bend in it...not much but I can see by holding it up against a straight edge....

Looks more & more like a valve, huh?

Okay, Hap - to HF to ask for a "magnetic base & dial indicator"....hope the instructions are good!!
 
You won't get the instructions for degreein' a cam with the tool, Tony. You need US for that. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif

Hap said:
So no more exuses big boy, go get yourself a magnetic base and dial indicator \:\)
Click to expand...

AMEN!!


Roll the pushrod on a REALLY flat surface, Tony. If it has ANY deformation it'll roll "funny".
 
Years ago we would use a pane of glass to check for pushrod straightness. Oft times it's straighter than a straight edge that's been banging around a tool box for years.

Colin
 
OKAY, I've cooled down...gotta go put tires on the Dodge truck this morning so will stop by HF & pick up a magnetic base & dial indicator....then, I'll try to get home early enough to check the valve lift (got an eye appointment in the early afternoon).

Still have to install the rebuilt brake & clutch master cylinders in the '74-1/2 GT after the last coat of paint I just put on the pedal box assembly dries.

& I need to run by the body shop to check on the '63 Midget.

Glad I don't have a job.......
 
It looks like you are tracking it down well- here's hoping it's the valve- but in case the problem is deeper- a semi-philosophical viewpoint:

We've all heard it said- you can restore a car a dozen times, it's only original once. The same goes for engines...well maybe you can't rebuild a dozen times, but you get the idea.

You have a well maintained engine there and it has a problem (even if the cam) that can be corrected short of a complete rebuild. I know that you don't want to have to open the engine up again in a few months and if this were a car with a less personal history or unknown provenance, I would say- rebuild it. But I, for one, would like to see how long a cared for 18V will run well with the original bore, rings and bearings. I would be tempted to repair (well, of course) whatever is wrong, but not go beyond the problem in order to keep it as original as I could for as long as I could.

'Everyone' has a B with a rebuilt engine. Howmany are running a near original engine with 200,000? Now there's something for the museum.

Just mt 2 cents...wait a minute, that took .2 hours....just my $40.00.
 
hehehehe....lawyers!!

Went by HF today to pick up a dial indicator....its always best to go on-line & print out any of their specials before going to the store...the indicator I wanted is normally $14.99 in the store but on-line was $7.99!!

No magnetic base though...they'd sold out....seems some guys are jumping on the indicators & bases & reselling on ebay...he'll have more bases next week.

Don't know what I'm gonna do but I'll not get to it at least until Tuesday anyway.....& I have worked hard to keep that car completely original since I bought it (heck, I finally gave in & replaced the top & carpet in 2004!)
 
The best way to keep it original is to "freshen" the engine at 50k - 70k miles.
Freshen= new rings and bearings and a valve job.
This helps keep the crank/ rods/ bore at original spec.

Running it out as far as you can will just accelerate the wear.

What did the ribcase look like on the inside?
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]What did the ribcase look like on the inside?[/QUOTE]
Looks like we've got a winner! Good to see you here, David!
 
If I suspect a sticking valve I generally do the finger test.

Put a finger on top of the rocker where it contacts the valve & run the engine...
If it feels 'funny' (different than the others)...Something is wrong.

Some people like to do the strobe thing.

You could easily just replace the valve guide, pushrod & valve.
Sounds like you're going for a milage record... /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
I'd be interested in knowing what the most miles on a original engine is.

Hey-Look...I made Obi Wan...Cool! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
 
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