MTFCA Forum

Got the '15 touring out and just doesn't run right. All cylinders firing but, pops and shakes at idle, no power, temp goes up quickly after stopping for a VERY short time but cools down once the car is moving again.....thoughts

A stuck open or burned out exhaust valve will give a constant popping sound at the exhaust pipe Very rhythmic sound that speeds up & slows with the engine speed. It doesn't go away. You can locate which cyl. it is by shorting out the plugs one at a time, That being said; you didn't say you had that kind of noise and your description of the symptoms indicate some other problem to me. Actually sounds like a timing problem. Low power, overheating etc.

Check the compression. If you have one cylinder with very low compression or zero compression. You have a stuck valve. A burnt valve but not stuck will run more smoothly at higher speeds, but won't idle smoothly. Popping in exhaust usually means some unburnt fuel is going into the manifold and explodes from the heat of the manifold.
You can also remove the valve cover and check the clearance. If one valve is stuck, you will notice it stays up rather than move up and down as the others do. You might even be able to see a stuck valve through the spark plug hole in the head.
Norm

John Seelman - Does the "popping" come from the exhaust or intake (carburetor)? Makes a difference in what things to check for. Also, was any work done to the engine during the time between when it ran fine, and when the problems you described started? Again, makes a difference what things to check for. If ignition work was done, I'd think ignition timing. Or, if any work was done on engine that could have caused a vacuum leak, I'd obviously suspect a vacuum leak,.....harold

......also, you said,....just got the car out,....if no work was recently done on the engine, but the car hasn't been run for quite some time, "sticky valves" could be the problem, in which case, I'd drive it for awhile with a bit of a bit of "top lube" in the gas tank to hopefully free up sticky valves. Like maybe a bit of 2-cycle oil in a fresh tank of gasoline, especially if the car stood for a long time with old gasoline (unless it was "non-ethynol" gasoline).

I put a new (rebuilt) NH on last Fall. Just got out means it was put away in November and fired up yesterday. I only use 100% gasoline.

I put the old carb back on and will try it over the weekend

To test for a stuck valve, turn ignition OFF and set hand brake, open throttle just past idle, then use the crank to spin the engine. You should be able to feel compression come up on each cylinder, one after another, at regular intervals. Each full revolution of the engine should have 2 compression events. All should be approximately equal. If an intake valve is stuck, you will likely hear air spewing at the carburetor when that particular cylinder comes up on compression. A stuck exhaust valve may make an audible sound at the exhaust outlet. This test will reveal a valve that is stuck in the open position. A "sticky" valve may seat at cranking speeds, but fail to seat at engine idle and running speed. Such a valve may have a rusted or gummed stem, and/or it may have a weak valve spring. I have had dirt dauber wasps build nests in exhaust pipes. This happened to a near-new tractor, and while it started and idled normally, it was low on power and sounded odd and the exhaust manifold got very hot. I had about decided that the turbocharger had locked up when the dirt dauber nest broke loose and flew out of the exhaust. Problem solved.

Put the old carb back on...still runs crappy

Have you checked for stale gasoline? It can really cause trouble.

New gas...100% gas

John there’s very little chance that a carb would cause the symptoms you described. There is some quite good advice given here IF you choose to take it. That being said is the popping constant and where is it coming from? What is the timers condition? Is it set correctly? Information is key in remote diagnostics.

Norman Kling suggested a compression test. I agree. If you find a cylinder with low compression, the next step is a leakdown test; you don't have to get fancy, I have used a tire valve with the core removed in the spark plug hole. A little portable air compressor will do. You don't need a lot of pressure - I have even used a portable air tank. Add air to the cylinder, listen for air coming out of the carburetor. If it is, you have a bad intake valve seal, if air is coming out of the tailpipe (you need really long arms or a helper) the issue is an exhaust valve. If you can see bubbling in the radiator it's a head gasket or something really horrible. Pull the oil filler cap and listen again - if air is escaping there you have a piston or ring issue. am assuming that you would know that the piston has to be at top dead center so that both valves are closed. Good luck, I hope that it is something simple.

I have seen these symptoms in 3 motors.

you have done the following?
1. compression test (expect 55-60# consistent in a stock up to snuff motor)
2. Shorted 1 plug at a tine (there was a strong noticeable worse running)
3. Adjusted carb mixture rich & lean & got expected changes. Then reset @ sweet spot.
4. Checked for strong exhaust pipe flow.(Rulled out a rats nest in the muffler)
Above procedures eliminate a bunch of possibilities.

Physically confirm valves are opening completely . Can look thru spark plug hole. measure opening. should all be around .250".
I would ask if you had did recent engine work. (say within 1000 miles.)

The 3 motors i refer to were popping & sniffing back thru the carb. & ran real rough.
#1. Immediately after a valve job. Exhaust valve seat too deep. Allowed for back pressure present when intake valve opened, leaning & blowing exhaust
gas back thru carb.

#2. My 14. ran well after complete engine overhaul with riley multilift jr's.
Slowly over time, it started running worse. @ around 500 miles it started intermittent popping. Got to where it would consistently pop & sniff @
idle.
Problem was valve stems wore AWAY & especially 1 exh valve was not opening enough. (see #1)

#3 Fellow club member. Same symptoms 100-200 miles on a fresh complete rebuild. Shorting plugs did lead us to #4 cyl.
#4 exhaust valve was not opening.
There was/is a batch of defective lifters running thru the hobby. Seems (intentionally spread?) 1 defective lifter per set. Heads were ground thru
surface hardening.
#4 exhaust lifter head was worn away. Gone.

The best advice you've been given here was, "Do a compression test".

Have you done that? All else is pointless without knowing your compression is good.

Compression test completed over the weekend the results; 40#, 42#, 42#, 45# on a cold engine

Next thoughts? timer gone bad?

At least they are fairly consistent. Read my previous post.

No recent engine work
pulled plugs grounded to block - have spark on each plug
free exhaust

I can pull the cover plates next and make sure the valves are opening

You may have a timer issue. if it worked well last fall, cleaning and oiling it will probably restore it. I'd also clean and gap the spark plugs. It is possible to get a spark to ground from all 4 plug wires and still have a timer issue, a weak coil issue, spark plug issue, or even a wire issue. A weak battery, non-working generator, or a magneto problem could cause low electric system voltage which could cause rough running. The wiring from the coils to the timer can short to ground and cause rough runnning.

The valves will almost certainly open, and they'll probably close at hand cranking speed. But they may not all close at running speed due to to rust or gum on the stems or weak valve springs. When you did your compression test, did you have the throttle wide open? A closed throttle can give a lower compression pressure.

Did you short out plugs one at a time whall running? You didnt mention. That would point out an offending cyl, coil, plug, timer contact etc.

If you pinpoint 1 cyl thats not effected by GROUNDING A SPARKPLUG, theres a bunch of easy tests. Like switch coils, switch plugs. If the problem changes cylinders, you found it. If not, it rules these out. No change, you look deeper - timer contact for that cyl., bad wire connections, stickey valve etc.
Its all about proper diagnosis by narrowing the field of possibilities. Not necessarily GUESSING @ the many of possiblities & still not finding that 1 specific problem that is dogging you.

Compression test done with throttle just past idle

As far as the spark goes....pulled all four plugs, still connected to wires and against the block, hand crank...all sparked in the correct order.

I start on battery(non-starter car) and switch to mag

My timer has been in the car for many decades with little maintenance other than the usual cleaning of the roller and contacts

Did you ground the spark plugs one at a time whall running??

You need to know if the problem is in 1 cylinder or intermitently different ones. Which cyl?
A plug that fires on the block may not fire under compression.
Does it run better or worse on battery or mag?

Not wild about the throttle not being fully open as it should be on a comp test but your #’s are consistent which leads me to other systems. Like ignition.

I have a new Anderson style timer from Langs that I can put on. The directions are fairly detailed but no pictures. The wiring is pretty much a no-brainer, the set up on the cam with the rotor, pin, neoprene seal, etc is a little confusing to me. Is there an assembly drawing?

Hi John.
Try taking the valve covers off. check to make sure you do noy have a valve pin missing or a broken spring. A intake valve may open & close well enough to do a compression test with no spring but not close enough when running. It sounds like you have tried about everything else. Also do you know if your car has a fiber timing gear? Hope you get back on the road soon.
Craig.

Replaced the timer last night. Here is the old flapper.... a very worn flapper for sure. Hopefully I have found the problem.
I'll check the timing, put a new set of plugs in, and fire her up this weekend

Thought I would set timing using this method. http://www.mtfca.com/discus/messages/59 ... 1472250621

Question, in the attached, the author needs to adjust #1 to fire earlier to make it similar to the others. Do you bend the contact as shown toward the center to attain the earlier fire desired?

John

Your flapper is severely worn and you need a new timer - this is the first evidence of any problem which would be connected with your trouble now that you have confirmed good compression.

you're getting ready to put the new timer on and see how it runs. Why on earth would you start bending on a brand new timer before you have ascertained that 1, it needed it for sure, and 2, it actually is defective out of the box?

if you start bending in it as new, you have just thrown another variable into the mix.

just put it on and enjoy your car

I agree Scott, which is why.....

I said I replaced the timer last night and try it over the weekend......

I also indicated that I was going to check the timing using the method in the article attached. The author had to adjust his contacts and I was just wondering if in his case the #1 needed to fire earlier did he bend the contact down to achieve the outcome he desired. I haven't checked mine as yet, also over the weekend.

I do appreciate your help

So the saga continues....

I put a new timer on and while it runs better, it still has no power.

I checked the timing per the procedure above in the link and the attached picture is what I had. 4, 3, and 1 were right in line. #2 was somewhat early.

Thoughts on next steps.....

Thanks for all the ideas

John[image]

I just did a search for "mouse" on this thread and found none.

you may well have an exhaust obstruction since it seemed to run OK in the fall and after a winter sit, it's lame. A restricted exhaust will heat the motor quickly, have low power and do pretty much what you described. Your compression is pretty average for an older engine. Your timing is not bad for an Anderson timer. At this point, I'd be inclined to yank the muffler and see how it runs then.

I experienced a plugged muffler once on my sister's old Mustang...had a new muffler put on for a trip to take my sister to college. Car would run fine at 35 but overheat severely in a short time on the highway. After weeks with a Mustang "expert" and many "fixes" to the tune of thousands of dollars. I was just a kid and didn't know much, but knew how logic worked and that damn car was fine until the muffler was put on. We cut the muffler open and found a piece of the down-pipe in it and once enough exhaust gas flowed through it, it obviously jumped up to block the exhaust. A few more weeks of rusting and it would have blown out, car would have been fine, and would have been a family mystery forever.

I just saw in the last picture, the part of the radiator I see looks a bit less than desirable.
Not saying that it’s your problem, but.
It doesn’t take very long running down the road under power to get hot with a poorly circulating radiator. But it should run ok, till it gets too hot.

I may have found the problem. Put a new muffler on and it ran much better. Needs more advance than previously, that may be due to the new timer...

You almost always have to readjust the length of the timing rod when going to an new Anderson timer. I would have thought that going from an Anderson to an Anderson wouldn't require it, but As worn as your old one was, it's been on there a long time and you may actually have two different manufacturers involved and that puts you back to "almost always fave to readjust..."

Glad the muffler did the trick...I should have caught that in my original post. Until you've experienced an obstructed exhaust, very few people will recognize it. Now you do.

The FIRST mention of a plugged muffler was in a Mar 23 post

I was very glad to hear that you have found the problem but I'm mystified by the piece of paper shown in front of the radiator. What does it depict?

Indicates when spark occurs at each cylinder.... A more detailed explanation is in a link in a previous post

Hudson29 wrote: ↑

Wed Apr 07, 2021 6:27 pm

I was very glad to hear that you have found the problem but I'm mystified by the piece of paper shown in front of the radiator. What does it depict?

Here is the post Paul.

http://www.mtfca.com/discus/messages/59 ... 1472250621

Not so fast......

Had the T out over the weekend. Again hard to start, no power at speed, have to run with almost all the way advanced to get it to smooth out at all. Reading some other threads, perhaps a leaking manifold?????

You could have manifold issues. There are several shade tree tests that can be applied before taking anything apart.