78 Camper Backfiring Low Power

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pdlrofdrms
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78 Camper Backfiring Low Power

Post by pdlrofdrms » Sun Apr 06, 2014 8:12 am

Hello everyone,
I am a novice VW mechanic. With the help of you tube, Colin, the samba, aircooled chris, and youtube I was able to rebuild my motor.
It took me 6 months.

But she purred and was driving greeeat. So much so that when Colin visited me last we had time to do things like fix my sliding door!

Now since then my bus and I have had a hard time. My front floor was so rusted out I had to install a new one. That black one you get from Bus Depot that in noway really fits.

I own a small business and a guy did body work on the side. Boasted how he could do that floor replacement in 2 days. Not so. Took two weeks, he did a poor job. Ruined my paint job, which I will have to address this summer, left big gaps that I will have to fix I was so overwhelmed I parked the bus for two months. Finally I had the courage to start back up again, I had to have the throttle cable assembly fixed underneath as he had welded it poorly too far back and my car was constantly accelerating.

I wanted to take my bus on a roller derby road trip to boise but I also had new Dakota gauges I wanted installed before my trip. I was so busy I took it to a reputable auto electric place.

However he was also over his head with the older VW. He loosened too many nuts. He called me told me what his issue was I ran down showed him where everything went.

He left my ignition on too long burned the points. He replaced them.
However when I got home I smelled fuel.
I started the car back up and holy shit fuel was dumping everywhere! I guess he loosened a fuel fitting in his wiring job.
UGGG..


So here I am. In Boise Idaho.

I made it.
BUUUT.

Its idling very low.
In fact , when I stopped in bend Oregon. In the am to head to Boise car would barely Idle.
it took me hours of trouble shooting.
I did another valve adjustment. All seemed fine.
Installed new points. Gapped. Tested with my dwell meter.
All seems fine.
But when I go to time it with my gun if I set it where its suppose to be. 8 degrees Before TDC it just idles very low.
It seems to be lacking power.
IT also backfires now in low gears.

The temp sensor shows the heads at the hottest up hill got 425 but not for long. On average the temp was 380-400.
Oil pressure shows 47 on the road 52 at idle.

I am using 15/40 wieght.

There is no pinging noise.

I did notice when under the car in bend or. The exsaust at the seam was leaking water. So maybe I have an exsaust leak?

Anyways,

This rookie needs help.

Thanks!

pdlrofdrms
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Re: 78 Camper Backfiring Low Power

Post by pdlrofdrms » Sun Apr 06, 2014 8:13 am

BTW I am on my way to play in a roller derby bout. So I can not check in till around 1pm. Thank you all for your help in advance I would love to fix this before I take her home.

Jivermo
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Re: 78 Camper Backfiring Low Power

Post by Jivermo » Sun Apr 06, 2014 9:05 am

Congrats on your '78. I have one, and I love it. Does your bus still have the fuel injection system? (I hope so) Vacuum leaks have always been the source of the majority of my problems. Please check all of your hose connections if you have not already done so. Don't just look; feel them and really explore. The last problem that I experienced that produced symptoms similar to those you describe was my fuel pump was retiring. How's the pressure? How are your plugs looking? Rich or lean? Perhaps some tweaking on the AFM. I've learned from Colin not to throw crap on the walls to see what sticks, but to review your systems with an open mind, and rule out the problem possibilities one by one. With these machines, keep the zen idea in mind: "Be here now". You will find it.

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Amskeptic
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Re: 78 Camper Backfiring Low Power

Post by Amskeptic » Sun Apr 06, 2014 3:32 pm

pdlrofdrms wrote:Hello everyone,
I am a novice VW mechanic. With the help of you tube, Colin, the samba, aircooled chris, and youtube I was able to rebuild my motor. she purred and was driving greeeat.

Now since then my bus and I have had a hard time:
*a guy boasted, he did a poor job. Ruined my paint job, he welded poorly.

*Dakota gauges I wanted installed took it to a reputable auto electric place over his head loosened too many nuts left my ignition on too long burned the points. when I got home I smelled fuel.
I guess he loosened a fuel fitting in his wiring job.

So here I am. In Boise Idaho.
Its idling very low.

I did a valve adjustment. All seemed fine.
Installed new points. Gapped. Tested with my dwell meter. All seems fine.
if I set timing where its supposed to be, 8* BTDC it just idles very low.
It seems to be lacking power.
It also backfires now in low gears.
On average CHT was 380-400.

This rookie needs help.
Hello, pdlrofdrms.
We have a problem that *must* be correctly analyzed before you drive further.
Please check your PM box for a Boise referral.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

pdlrofdrms
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Re: 78 Camper Backfiring Low Power

Post by pdlrofdrms » Mon Apr 07, 2014 8:00 pm

Well for better or worse I drove her home. I wish I would of checked this again before I hit the road.

So things in my initial assessment that were incorrect.
Overheating.
The reason it was not getting hot was because the ambient temp outside was very cold. When I started my trek home it was much warmer out and just driving on the freeway at 60 caused the heads to creep up to 425-433. I drove her at 45 mph to keep it under 410.

I also decide to pull over and wait till dusk . I drove all night at modest speeds and was able to make it home.
I noticed also that the TDC dot is not steady when timing, Its jumping side to side. As if its getting inconsistent information.

Also forgive my novice I am guessing its name because while I did know its name last year I can not recall it right now: I think its the brake booster hose? That big black hose with the fitting in the center of the two.
Its the big black tube that comes through the fire wall and that goes across 3 and 4. When I sprayed it with Carb fluid the car increased idle. ( this is a sign of a vaccum leak correct?)
I have a vacuum tester so I will check for sure tomorrow.
It was a place of an original leak and I really tried very hard to repair it. It seem to hold but maybe its finally is breaking down. Apparently this is not a part you can purchase.

Those are things I just noticed with my rookie eyeballs and I plan on spending all day Tues and Wed ( days I was planning on camping and enjoying the country side) to give a good look at the motor.

Any ideas would be great.
I will report back asap on compression. Last compression check I did was 6 months ago and each head was at 120 even steven.
So it will be interesting to see if there has been a change.

Thank you all for being here. I was so stressed out on the road. I had the distributor out so many time.
New tools I am adding to my travel box...
Magnet wand and grabber tool
better light
Tools I will take next time:
Compression tester
Vacuum tester


Things I am going to check immediately in the Am is Vacuum and compression.

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airkooledchris
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Re: 78 Camper Backfiring Low Power

Post by airkooledchris » Mon Apr 07, 2014 9:05 pm

damn, I wish you would have continued to text me while out on the road so I could offer assistance.

my schedule is nuts this week, but late morning Saturday (I have a gig Friday night so not too early) I should be available if your still troubleshooting. we can always rob parts off mine if needed, since it's in a million pieces in the garage anyway.

there may be multiple issues, but a vacuum leak is definitely one of them. (that surge from the carb spray confirms it)
1979 California Transporter

pdlrofdrms
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Re: 78 Camper Backfiring Low Power

Post by pdlrofdrms » Tue Apr 08, 2014 1:44 pm

Okay so I am in the middle of assessing two things so far:

1. here are the results from the compression test

Cylinder 1: Dry: 120 Wet 140
2: Dry 110 wet 120
3: Dry 115 wet 120
4: Dry 130 wet 145

And what is that metal box on the fire wall on the passenger side? Some sort of relay switch? It was unplugged!

Okay out for the vacuum test!

So far those compression numbers dont scare me. But its odd how 2 and 3 are way lower.

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Re: 78 Camper Backfiring Low Power

Post by pdlrofdrms » Tue Apr 08, 2014 3:01 pm

I did not even have to get the vacuum gauge out! def a vacuum leak at the check valve on the brake booster!!!!

I don't think that is the only issue. But its a huge one.
I think and probably worked in my favor due to this leak but the gas pedal is welded too far back so by the time I am floored its only going 55 mph. I knew it was in the wrong spot when I put my mat back in and I had to make a cut to make it fit.

Okay so I need to do some homework and figure out how to fix this. The hose is so old that the teeth on the check valves dont seal it.
What I did last time was put a silicone inside the tube inserted the check valves and used fittings to secure them even tighter let sit for a week to dry completely. Seemed to hold. Guess not.

Any ideas?
because apparently you can not purchase new molded hoses to replace these.
That was last year. I will check today.
Maybe its changed.
or maybe you all know where I can look.
Thank you!!!!

pdlrofdrms
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Re: 78 Camper Backfiring Low Power

Post by pdlrofdrms » Tue Apr 08, 2014 3:20 pm

viewtopic.php?t=6565

Found this!!!

YAY.
On a mission I will report back soon
No driving the bus. Got it!

pdlrofdrms
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Re: 78 Camper Backfiring Low Power

Post by pdlrofdrms » Tue Apr 08, 2014 6:50 pm

K I am at "stuck" place.
My original brake booster check valve did not have a nipple on the side.
When I was working with Arcata German Motors they replaced my old one with one with a nipple on the side.
It is currently sucking in tons of air.
What is this for?
If I plug it, the car wants to die. If I leave it, it idles but roughly.
Mmmm...

Rookie perplexed.

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Re: 78 Camper Backfiring Low Power

Post by pdlrofdrms » Tue Apr 08, 2014 7:24 pm

it was in backwards
Douh!

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Amskeptic
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Re: 78 Camper Backfiring Low Power

Post by Amskeptic » Wed Apr 09, 2014 7:46 am

pdlrofdrms wrote:it was in backwards
Douh!
Wow, you are blasting ahead of me here.

OK. Compression looks thankfully acceptable after all of that driving with a vacuum leak.
(your engine must like you)

You can use any hose that works in a pinch . . . just promise the engine that you will find the correct stuff.
The brake booster hose, is it not a plastic tube with rubber inserts and white plastic clamps at the check valve in the engine compartment?
Colin

Image
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

Jivermo
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Re: 78 Camper Backfiring Low Power

Post by Jivermo » Wed Apr 09, 2014 8:26 am

Rule 1: It's always a vacuum leak.

pdlrofdrms
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Re: 78 Camper Backfiring Low Power

Post by pdlrofdrms » Wed Apr 09, 2014 10:34 am

Amskeptic wrote:
Image
YES its that black tube with the white plastic clamps. Although mine did not have white plastic clamps. :-) they must of been sacrificed over the years.

I think its the check valve...we will see. I am doing some investigating today.

What I did to make the valve fit in the tube because the tube was too stretched out on the flared ends that it would not hold the barbed ends, I used heat shrink for electrical around the barbed ends and poof magic. I was super tight. Fit like a glove. BUUUT I think the valve is broken. We will see.
I thought I had it in backwards because it was sucking in air like a fish. Then I turned it around and the brake peddle was so hard to push down it would barely stop.
BUT no vacuum leak. mmmm...

Airkooledchris came over and he figured out #2 spark plug wire was causing #2 to miss. Changed the spark plug wire adjusted the idle and its idling great.

More detective work ahead.

pdlrofdrms
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Re: 78 Camper Backfiring Low Power

Post by pdlrofdrms » Wed Apr 09, 2014 3:09 pm

okay ready here is my rookie diagnosis:

Today I went purchased a new check valve intalled. And immediately it failed. I took a peek at it and there is oil in the vacuum line and now in the check valve allowing air flow both directions.

Mmmm...
Investigate.

Here is my theory. A few months ago I noticed when I depressed the brake pedal it made a wierd noise. But they work. I am thinking I must be crazy it must of always done that. I went back and forth and told myself you should check that out soon. I don't think its a normal noise.

Fast forward a few months later and the car as called me to attention.

I think what happened is the master cylinder was going bad, which inturn leaked into the brake booster, which then caused the booster to fail, that allowed oil to get into the vacuum line which caused the check valve to fail, which then caused the vacuum leak because Arcata German Motors put a check valve in that had a port to the side of it. I am assuming it was for emissions but I am not sure.

But it was sucking in air with a lot of pressure.

I then install new check valve and no leak but no brakes either.

The peddle is hard to depress,
So I just wanted to run this by you all to see if I should check out something else first or if yes the booster and Master Cylinder need replacing.

I found them on Wolfburg West.

locally no body has these parts.

Is it possible to rebuild the brake booster?
And why is it called a servo on some sites?

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