Loosing power uphill or under load any ideas?

[Worby876]

Hi Guys,
I think I made a little bit of progress today.

First I started the motor on LPG and she was a bit slow to fire and finally coughed
to life after a few cranks but idled pretty rough...like i thought there might be a hole
in the extractors..but after a minute of keeping the revs she settled down ...so
Im thinking yeah.. one or more of those valves are not performing right because the
the push rods are not tensioned right yet.

OK , I then took the rocker cover off and started to remove the spark plugs and the one in No#4
shattered...its brand new..just put them in at XMAS and have done less than 20KM.

then I noticed NO#5 plug was cracked...Hmmm did that happen before and this was what the fuss was
or did I some how break it getting it out..they were a bit snug ..my son Michael put them in when we
did the head gasket so maybe he did hem up a tad tight??   

Next..I started to take the compression test for each pot using a new gauge I purchased from Supercheap.

I screwed the adapter in each spark plug hole finger tight and then the gauge assembly, cracked the engine over 5 times and noted the pressure. they were all pretty much right on 150psi.
 
With the Exception of cylinder no# 4 which was down... at only 130psi. 

I checked all the push rods and most I could easily "twiddle" with my fingers...
So I thought OK these do need some adjusting and tightening up as per the posts here before.

I  too the radiator shroud off to try and get some purchase on the fan belt while moving the fan around
clockwise but didn't seem to be able to turn the motor, as I kept an eye on the rotor button in the dizzy
and the valves and rockers,  hmmm this might be a two person job.

I was running out of daylight but thought I would at least nipp up the rocker assembly over the No#4
pot got the torque wrench out set at 42nm and it clicked right away, so I did a 1/4 extra turn and noticed
I could no longer "twiddle" the push rods....I re cranked the motor and the pressure has come up almost to
150 Psi (maybe 145 or so)...

I want to do the procedure from No#1 right through to No#6 but the motors gonna be stone cold by morning
so I guess I have to put it all back together , run the motor warm again and start over...but I need to figure
an easier way of turning the motor over by hand..may need to put a couple of bolts in the harmonic balancer
and use the big flat screw driver as a lever to pull it around...not much room though with the radiator in the way.

Oh and Im gonna need to replace those two spark plugs..still...I think I made some progress...

Will see what tomorrow brings....and then I will check the other matter regarding possible issues with the LPG..but
I kind think its really the Rockers, push rods and valve set up that caused the main loss of power under load and missing and back firing etc...or maybe its a combination of several things...

Cheers

Cheers

[John Abbott]

Thats the way Worbs....Slow and steady. Its a process of elimination now

[Rothu]

You won't need to put it all back together to warm up the engine. since they are non-adjustable rocker posts, you can do it cold. The adjustable ones are the ones you need to have the engine warm to set properly.

[Worby876]

aahhhh !!! this is really starting to get to me !!

I put it all back together...started on LPG but again still rough as guts until she warms up
with revs and then she returns to a smoother idle but once I take the foot off the accelerator
she's really lumpy and finally dies !!!

So I restart with ULP (petrol) and she idles fine at around 550 rpm just like text book
the motor warms but doesn't get Hot Temp gauge still at bottom hardly off from dead cold.
So the cooling system is all good.
I can rev her up to 3500 Rpm and all good..(not game to take her above this even though I saw some
one else on a similar post say they could rev their stock LPG run 202 to 6,000 RPM !!!)

Ok, so I know something is not quite right on LPG  (I figure  I can address this later) so lets try her
on petrol.

I put the van into 1st start to drive up out of my drive way and I can tell she is hesitating  under load
I roll back and try several more times...I know I can really give lots of revs to force her up the drive but
thats not the point she should easily do it with plenty of confidence...thats the real thing now..
I just don't have confidence...something is not right but I cant figure what it could be.

the Engine starts fine and idles fine , it revs fine, its got 150 psi in 5 pots and 145 to 147 in No#4
still pretty respectable...its got new spark plugs, Oil level is fine, coolant level is good, I can see the green
water in the expansion bottle...and temp is fine all good.

Something is robbing power under load...could it be a sticking valve?? maybe one or more of them got out of shape
before...when she did that massive back fire that blew the exhaust box apart a few weeks ago after i had done the head gasket...but maybe not properly set the rockers, pushrods etc as per this discussion.

If I don't have confidence to even drive her out of the drive way...Im not gonna have much confidence to take her for a real test run to see how she goes on the open road.

Anyone got any further ideas? Maybe if I could post a video of how she starts and sounds on LPG and then on Petrol
and how she hesitates and such when under load???

How do I post a video? on this forum?

Cheers

[Rothu]

So you did reset the lifters? If you use a vacuum gauge from a point on the inlet manifold, that will also show you a lot of what is actually happening. This site shows you all the scenarios that can occur.
http://www.secondchancegarage.com/public/186.cfm

Remember lpg needs advancing on the dizzy.

[Worby876]

I didn't reset the lifters, as I was led to believe because I hadn't removed them when i did the head gasket exchange
I didn't need to..and something about only really knowing on a dyno test if they needed attention.

I did retention the two valve rockers over the NO#4 pot until I could no longer get the push rods to "twirl" in my fingers and got the compression back up to near 150 PSI.

I wont be able to do this systematically until I figure an easier way of turing the motor over slowly by hand
to determine TDC for each cylinder. So on that point I know I could still be in trouble..although the motor seems to idle nice and not making any funny noises from the tappets etc except when running on LPG until she warms up a bit.

I happen to have two vacuum gauges permanently mounted in the cab, a great big one on top of the dash above the steering wheel marked idle, drive, economy and poor etc. and another smaller one marked at HG 0 to 60
next to the Volt meter. (Dad must have had these set up before when he had the Beddy  )

Thanks for the website on how to use the vacuum gauge to test or diagnose whats going on inside the motor.

On Petrol (ULP) The Motor pretty much sits solid on 20 at idle and all the way to 3,000 RPM on slow stead acceleration and showed none of the symptoms as indicated on the website.

On Gas (LPG) she was fluttering between 10 and 15 until she settled (as the motor warmed up or the Gas converter warmed) and remained roughly near a steady 20 (maybe 18 or 19) but was no where near as smooth on acceleration, and if I gave rapid acceleration and took my foot off quick she would invariably stall.

Now I have been giving this all some more thought and one thing that was done before after the head gasket was
replaced but BEFORE the big backfire incident that blew the muffler apart and the first time I experienced a rapid loss of power under load...and that was the fact that the local LPG gas inspector that did my re certification replaced the
gas shut off valve and relay switch assembly unit as he claimed it was leaking !!! (yeah right..I never noticed any loss of gas but I guess they make their money some how.  ) im re looking at dads notes and set up here http://gallery.oldholden.com/Jack_s/Jack-s_001/ and here http://gallery.oldholden.com/Jack_s/LPG++Parts/

Still I cant see how that would affect anything either the gas is on or its off eh?

I will check the timing tomorrow with the strobe light to see if that gives any clues.

BTW I fiddled with Dads device http://gallery.oldholden.com/Jack_s/Adjustable+Distributor+Settings+whist+on+the+move/ that regulates the dizzy forward and back 6 to 10 degrees and it actually worked worse in the Petrol position when on ULP so i left it in the Gas LPG position where it idled much better.

Maybe the strobe light will confirm if this is set up correctly or has somehow been "upset" recently...I never made any changes to the dizzy or its current setting so its a bit of a mystery.

Something to think about over night while I go to the movies to watch Fast 5 with my son.

Cheers

[Rothu]

I didn't mean reset the lifters as in remove them, I meant the process of loosening all the rockers and manually turning the engine over for each cylinder to TDC and then torqueing down the rockers for that one. As discussed previously. I still believe that since that wasn't done when you did the head gasket, it has caused the lifters to not be compressed properly and so fluctuates the valves. You'll still have compression for each cylinder, but when all are operating and some valves are opening and closing at non-appropriate times, you'll be losing lots of power under load, backfiring, even if it idles fine. and as you say, it's hard to start.

I had exactly the same symptoms as your petrol and lpg notes. The even weirder one was when the push rods were bent, which you'll see when you twirl the rods whether they are straight or not. But I'd really follow the procedure of setting the lifters properly to eliminate that possibility.

The gas shut off valve and relay switch assembly unit will either give it gas or not.

[Warren]

BTW I fiddled with Dads device http://gallery.oldholden.com/Jack_s/Adjustable+Distributor+Settings+whist+on+the+move/ that regulates the dizzy forward and back 6 to 10 degrees and it actually worked worse in the Petrol position when on ULP so i left it in the Gas LPG position where it idled much better.

Buy your statement here I believe your timing is out. If the motor running on Petrol works better in the LPG setting and rough in the Petrol setting then it is out by around 6 degrees (going on your dads settings)
 
If an engine runs to far advanced it will do the things you have said.

So Adjust your lifters and check/adjust the timing, maybe your dads Ubeaut arm is bent.

Warren

[Merlin]

sounds like distributor troubles to me . its time for the KISS principal here .1#check for true tdc ,Holden sixes have a habit of spinning the harmonic balancer giving a false tdc,2#check the distributor for wear/play in the shaft & advance plate check the point gap ,gas needs a stronger spark than petrol .I dont believe your lifters are hydraulicing as it would have run rough immediately and just a curve ball check the dizzy cap for cracks as that is a notorios cause of backfiring    Cheers Neil

[Worby876]

Back from the Movies..not a bad flick that fast 5 the last of the fast and furious series.

Thanks fellas for your suggestions I will try and check them out in the morning as we have
yet another long week end here in Sunshine state 

I bought a new timing strobe light..never used one before but Im gonna give it a go
and see what I discover.

I will try to post a few more pics and even a video if I can...might need to be a link from Youtube
as Im not sure if you can post a mov. file or similar here.

cheers