Can't figure it out myself. Reaching out for help

[tom'sB2B]

Hi Everyone

I've been trying to figure out an engine "power" problem for months. Finally throwing in the towel and reaching out for help.

Last fall, while driving the truck home from a short ride, I found that I was loosing power going up hills. I live on a rather steep hill and by the time I reached it, I could barely make it up in first gear.

     This is what I've done so far without fixing the problem

1. Checked and change transmission fluid, checked fluid drive fluid

2. Changed plugs, condenser, cab, rotor,

3. New vacuum advance

4. Replaced in line fuel filter and checked fuel pump (seems to be working fine)

5. Checked timing with light and vacuum gauge: about 4 degrees btdc, 60-65psi

 

Now, with any load I get a popping out of the carb. and still no power

I'm guessing I still don't have my timing right. I will go back and check my points gap.

 

What am I missing?

Should I be thinking about another carburetor rebuild?

 

Any help is appreciated

Tom

 

 

[Don Coatney]

Have you done a compression test? Or checked vacuum readings?

 

 

[tom'sB2B]

Thanks Don

No I haven't

I'll get busy on that.

[Jeff Balazs]

Tom;

What sort of a vacuum reading are you getting at idle? You should see a fairly steady needle at 17" to 21" at idle. Anything other than that should pretty well tell you where to look.

 

One potential problem area that doesn't seem to get a lot of attention here is carbon build up in these engines. I was running into this a while back and have found a simple cure. I believe these modern fuels combined with running in traffic cause these flatheads to get a fairly heavy build up of carbon which adversely effects how well they run. We have a lot of steep hills here and things were getting steadily worse until a old buddy suggested I try some Chemtool fuel system cleaner. I did and got very good results in just a few days. Now I put a can in every 3rd tank. The old truck runs better and better all the time. Sure made a believer out of me.

 

Hope this helps, Jeff

[clarkoh]

Compression and vacuum are a great place to start. If the carbon is an issue, we used to slowly feed a couple cups of water into the carb while revving the engine slightly. I understood the steam generated helps the carbon pass through the tailpipe. A couple other possibilities might be a warn camshaft lobe or maybe it needs some more timing. A broken valve spring is possible causing a valve to not shut properly? Good luck.

[NiftyFifty]

NEVER AND I MEAN NEVER pour water down any carb or in any engine!! Water of course is non combustible, and such can and will cause it to hyrdolock and has ZERO ability to remove carbon. Sorry if this seems like a harsh reply, but that's bordering on dangerous advice. Use carb/intake cleaner or something like Marvel Mystery Lube and pour it very slowly down...something that will burn, and has carbon/varnish removing capabilities, but again...not too much to where you could lock the engine and cause damage. With spray I will run the engine for about 3-5 mins giving it spurts and letting it clean itself out then again and finally I will stall the motor out with the spray and let it sit about 30 mins, then restart...but I'm just choking it/flooding it out...not causing a locking issue.

I'm a huge fan of the Marvel....it's amazing stuff, and free'd up my stuck rings last year.

[Jeff Balazs]

Water is not something I would ever intentionally introduce into an intake. Good way to damage a spark plug at the very least and possibly quite a bit more. Just not one of those old school ideas I can get behind.

 

I also do not like the idea of pouring quantities of fuel system cleaner or oils directly into the intake either. It may have it's place in some 2 stroke technology but this practice can cause just as many problems as it solves in a 4 stroke engine. I think it is much safer to go after this carbon with a slower more controlled approach.......like a tank or two of treated fuel.

 

Jeff

[tom'sB2B]

Well I just finished a compression and vacuum test. Here are the results

 

1. 125psi

2. 130psi

3. 125 psi

4. 120 psi

5.   10 psi

6.   10 psi

 

vacuum test:  fluctuates between 13-17 "

 

Looks like I need a head gasket. What do you think?

 

I think I will use the fuel system cleaner after I get everything fixed and timed properly. Definitely a lot of carbon on plugs and out tailpipe.

[greg g]

You mentioned new vac advance, are you sure it is getting a good vacuum signal and is it advancing the breaker plate. How does your loss of power present itself? Gradual loss of rpms, bucking and surging, does it only happen on a hill or does it present after a steady acceleration on a level road ?

Just noticed your compression test. Those readings indicate your head gasket has failed between Cylinders 5 and 6. A very typical failure.

Edited July 4, 2016 by greg g

[tom'sB2B]

It was never a gradual problem. I noticed right away when I was trying to make it up the hill to get home. I could usually make it up the hill easy in second gear. Now I can barely make it up the hill in first. I first thought it was a timing problem or a vacuum advance.

[Don Coatney]

In most cases a compression test is only to confirm what the starter motor tells you. A healthy engine starter will spin at the same speed. With a unhealthy engine the starter motor will spin faster on the low compression cylinders.

[NiftyFifty]

??????? Don... A compression test is an essential part of figuring out what and where the problem is...and the addition of oil down the cyl can help to identify ring pressure loss, or valve issues...but I'm not sure why we think it's just a head gasket issue....unless we have white blowing smoke out the tailpipe or oil in the coolant...it could be a number of things that have made this engine lose power and from the test, we now see compression. Your starter motor is irrelevant in the equation...you can test compression with a crank if you had too....or in a two stroke or small engine application...a recoil /kick start.

Pulling the head is the thing too do, but a stuck valve , or cracked ring(s) could cause similar issues

[tom'sB2B]

The starter motor doesn't really seem to fluctuate greatly to my untrained ear. Am I safe to assume that the head gasket is the main culprit to my problem?

[Jeff Balazs]

Tom;

Pretty obvious to me at least that your head gasket has failed. You know what to do there.

The additive I mentioned will help keep carbon build up to a minimum. I am a huge advocate of adding a good vacuum gauge to the cockpit. It will tell you when you have a problem ....... and help diagnose the problem too.

 

Jeff

[tom'sB2B]

4mula-dlx..sorry I just read your last post. I guess I will pull the head and hope that the gasket is the problem, but cracked rings or a stuck valve could be it too. Yikes!

[tom'sB2B]

I'm moving in a few weeks. So, this is something I think I  will have to wait on. I can at least drive it the three miles to the new place instead of having it towed.

[greg g]

Most head gasket failures on these engines are dry failures between siamesed cylinder pairs, and the majority occurs between 5 and 6 as that is probably the hottest section of the engine. When the failure occurs there, there is a loss of compression into the neighboring cylinder through the gasket rupture. Typical of this failure is that there are no coolant passages involved so no smoke and no coolant lost to the crankcase, and no chance of oil being involved. Just a loss of power associated with running on four cylinders and misfiring on two.

As long as it will restart and your route is level the truck should be able to relocate under its own power, but keep you eye on the gauges.

[_shel_ny]

Quoted from  the interweb:

 

opinions vary .  Of course just because it is on the web does not make it true.  Nor does it make it false.

 

""I guess you just can't assume that people stop and think about these things...

The mist thing...
Well, misting it is just fine (but too da.....easy), but back in the day we just filled a cup of water, revved the engine and dribbled the water into the carb.

Why it works...
Along the way from the cup to the combustion chamber, the water is joined by its buddies, fuel and air. Upon reaching the combustion chamber, the fuel and air perform an erogenous feat called combustion. This excites the water to the point of instantaneous vaporization. When this happens (as I assumed all knew) the volume of the water expands. Since it's instantaneous it shatters the carbon deposits and all the participants then try their damnedest to pop out your exhaust.

Does it hurt?
Undoubtedly for the carbon, your motor loves it, just don't dump a whole cup in at once.""

 

And:

 

 

"Yes, I have done this in the past. A few times. It does work, as illustrated by the knowlegable posts preceeding this one. A mist of water injected into the air stream and sucked into the combustion chamber will, upon ignition of the air/fuel mixture, explosively turn into steam. This does indeed have the effect of quite literally steam cleaning the carbon deposits from the piston face as well as the faces of the valves. The heat of the combustion chamber will completely eliminate any danger of rust from the components exposed to the vapors.

The best technique is to manually open the butterflies while spraying the water into the carb opening (works with TPI systems also). If the volume of water is a little bit excessive it will cause the engine rpms to drop, but by controlling the butterflies with your fingers you can prevent the engine from dying. Just back off on the water spray for a few seconds and let the idle speed return. Keep the idle speed up to around 1000 or so."

Edited July 4, 2016 by shel_ny

[NiftyFifty]

Why would anyone think that "steam" is a better cleaning agent then something that was designed to remove carbon, and be safe for the engine? Just because someone has done something and they think it helped, it doesn't make it right...I'm sorry, but in no fashion is adding water an acceptable thing to do on any engine, no matter how slow. Steam can also hydro lock a cylinder and incur damage, and water also washes cylinder walls, which removes the cross hatching.

This reminds me of the diesel mechanics that throw comet powder cleaner in the intake of the engine to scratch the cylinder walls to stop oil burning....works likely 1 outta 100 times, and just long enough to sell it to he next poor guy.

[greg g]

http://www.gizmag.com/bmw-water-injection-efficiency-power/38289/

[TGP]

Blown head gasket between #5/6

Cly.

Compression readings indicates

This.

Tom

[NiftyFifty]

http://www.gizmag.com/bmw-water-injection-efficiency-power/38289/

First I've ever seen of that...but still has zero to do with pouring water down the carb of a flathead engine to remove carbon, your comparing something specifically designed to introduce tiny amounts of water into the plenum for cooling, too someone pouring water directly into the fuel system of an engine designed 75+ years ago

[Young Ed]

There is a guy on the 39-47 truck forum with a water injector on his truck. He said he'd give it a little squirt of water on occasion and his engine was carbon free. My Dakota would get carboned up and ping on occasion and we'd let seafoam get sucked into the intake and clean it all out.

[Don Coatney]

As I said "In most cases a compression test is only to confirm what the starter motor tells you. With a healthy engine the starter motor will spin at the same speed. With a unhealthy engine the starter motor will spin faster on the low compression cylinders."

 

I never said this replaces a compression test. I said this confirms that a compression test is required.

 

If you listen to the first few seconds of this film clip you will hear the starter motor speed up and slow down as it spins the engine indicating at least one cylinder is down on compression..

 

 

I have used water down the carburetor to de-carbonize several engines in the past. As you know water in a vacuum boils and vaporizes at a much lower temperature. So as soon as the water droplets enter the intake manifold they change state from a liquid to a gas and effectively steam clean the combustion chamber. I have never experienced any damage to an engine when doing this.

 

So that is my opinion on these  subjects. You can agree or disagree or agree to disagree, your choice.

[Jeff Balazs]

When you do something like this you are essentially shocking the carbon loose. It can break away in chunks and not all of it may go exactly where you want it to go. Heavy deposits of baked on carbon is abrasive stuff not something you want lodged down in between a piston and a cylinder wall. Or getting hammered into a valve seat. Also when you do something like this you run the risk of having the ceramic nose of a spark plug let go. This is never a good thing. There is just no way any engine or spark plug manufacturer is going to condone this process.

 

I believe it is best to go about dealing with this much more carefully. I drive my truck daily and there is no question in my mind that this engine is prone to carbon build up. I can't say if this is due to modern fuels and driving conditions or if it was always a problem with this design. What I do know is that if left to build up it has a negative effect on how well it runs. I have been using Chemtool fuel system treatment for about 4 or 5 months now and I am positive that it has eliminated the problem. No doubt there are other such fuel additives that would work equally well. Unlike water this method of treatment takes a while to work .....but work it does.

 

Jeff