1911 Engine Will Not Start

[MochetVelo]

This one is mystifying me thus far.  A 2-cylinder 1911 Renault AX which ran when inspected a couple months ago, but does not start now. Any ideas? Here is my analysis:

 

- Engine has good compression (lots of hissing on compression stroke).

 

- I lapped valves & seats, and timing seems correct.

 

- Newer plugs get good white spark. I set timing correctly, I believe. Rebuilt magneto.

 

Fuel flows to carburetor freely (a Solex M). I cleaned and checked carb a couple times, and replaced gaskets. All orifices are clear. However, I am not certain fuel is being sucked into the cylinders as the plugs stay dry and no smell is detectable from tailpipe. Fuel also get puffed out the carburetor air intake. A further odd thing is that the fuel does not ignite at all despite use of primer cups and directly squirting into spark plug holes.

 

Phil

 

 

[edinmass]

Use a borscope and check the timing at top dead center and the valves are closed. Also on 99.9 percent of all engines, the keyway is at 12 o'clock at top dead center. 

[60FlatTop]

The valves are exposed so you can bring it to TDC and rotate it in the operating direction saying what each valve is doing out loud. I do that with OHV engines to get my bearings.

 

I would put the "old" plugs back in for a try as well.

 

You are lucky. You did the work. That eliminates a whole bunch of possible things that could have gone wrong.

[MochetVelo]

I think the timing is correct in the engine. It's set in an interesting way: There is a bolt atop the front cylinder (which has been removed in my photo). You drop a thin rod down which rests atop the piston. The spark should occur 8mm before TDC according to marks you make on the rod. The valves seem to be timed correctly, they seal on the seats, and there is some valve lash.

 

Phil

[JACK M]

Yes, I like the interesting method that you mentioned. But the TDC could be 180 out.

Try putting your finger on that hole and crank the engine. 

[Mark Shaw]

1 minute ago, JACK M said:

Yes, I like the interesting method that you mentioned. But the TDC could be 180 out.

Try putting your finger on that hole and crank the engine. 

I agree, you must verify that both valves are closed for TDC.  Set it at full retard to spark just an inch past TDC on the flywheel. 

Even a two cylinder can break your wrist if it kicks back. 

[F&J]

I agree that the mag is not timed correctly, like 180 out.  it's sparking with piston at bottom or with one valve opened fully.

 

Take both plugs out but put the wires back on the plugs laying on the head.

 

Get a helper to spin the crank while you have a thumb over one plug hole.  Doing it a few times to get eye and brain coordination, you should be able to see if it sparks WAY away from the last push of compression.

 

 

[MochetVelo]

My helper (a better mechanic than I) says the timing looks OK, but I will check again. In this engine, the magneto (like the 2-cylinder Maxwells) fires both plugs on both the compression and exhaust strokes, so 180 off should still work, no?

 

Phil

[DavidMc]

With the Maxwell 2 cyl. the spark occurs  on both cylinders every engine rotation, one cylinder is on compression, the other on exhaust .  Both are at or near TDC , fully retarded .  If it was 180 deg out both would be at BDC.    I don't know if its the same for the Renault

[MochetVelo]

I worked some more today. The Bosch magneto has two cams 180-degrees apart. The bottom cam works the front plug, the top cam the rear plug. I believe it makes one revolution per turn of the crankshaft. I think I have them firing correctly, but still no ignition.

 

Phil

[Tonz]

I've started many old motors over the years, and always made sure of the 3 vital ingredients ... Spark, compression and fuel.

So work on each of these one at a time.

Some difficult ones had things like plug leads crossed, maggys 180 out, a points cam in back to front, and an absent condenser. These are the things that you discover 2am in the morning when in bed trying to go to sleep.

So I reckon check and test each ingredient, you should get it going. Good luck.

[Pete O]

You mention fuel being puffed out the carb on intake.   I wonder if your valves are timed correctly?  How did you line up the timing marks on the crank and cam gears when assembling the engine?

[NewOldWood]

It ran a couple months ago, what's been done to it since then?

[1906 lozier]

bad fuel...too old..had this problem just today trying to start my Bentley. fill the fuel bowl with new gas and see if it starts.

[MochetVelo]

Nothing has been done to the engine since it ran a few weeks ago. The gas from then was drained when the car was shipped to me, and I refilled it with 1-year+ old non-ethanol fuel. It does act like the gas is bad, so I tried lighting some and it burned readily. However, I will try filling the bowl with some fresh gas ...if I can afford it!

 

Phil 

[edinmass]

Drain the fuel from the carb, shut off the fuel. Try getting he timing right and crank it over with the starter and give it a touch of starting fluid…….don’t get burned! Use it sparingly. If it doesn’t have an electric starter, then that’s  another ball of wax. If it ran a few weeks ago, you timing is a mile off. You need to check position/valve timing before you play with the mag.

[Guest]

Are the priming cups sealing properly? Could the hissing sound on compression be a leak somewhere?

 

Here is a timing diagram from Omnia in 1908. The data for Sizaire et Naudin was spot on so I assume the Renault info is also good.  

 

The article was translated into English and published by SAE, copy here:

 

https://www.jstor.org/stable/pdf/44579465.pdf

Edited May 17, 2022 by Andrew46Coupe (see edit history)

[Guest]

July 4th 1908 Omnia article on the new 8HP Renault voiturette.

Edited May 17, 2022 by Andrew46Coupe (see edit history)

[MochetVelo]

That Omnia article is very nice. Thanks for posting it. I actually found an original Renault carb which I may try to install in the AX. Meanwhile, I think the problem lies with my current carburetor, the Solex MV ("V" meaning vertical). The timing (ignition & valve) in the car is correct, in my opinion, with plenty of suction through the intake. I do not believe fuel is entering the engine, however. It's a simple carb, and I've cleaned it out, replaced gaskets, etc. After several cranks, the intake tube is completely dry and no smell of raw gas out the exhaust pipe. 

 

Phil

 

 

Edited May 17, 2022 by MochetVelo (see edit history)

[Akstraw]

If the timing and spark are correct, it should fire once or twice per cylinder with gasoline directly to cylinder from the priming cup, or with starting fluid through the spark plug hole.  From the diagram of the carb, a little starting fluid thru the air intake should work, too.  If any of these work, then you know the spark and timing are okay, and the issue is with the carb.  If they don’t, then go back to spark & timing.  Don’t overlook the easy stuff, either, like checking for blocked fuel filter or fuel line, or even having run out of gas, for that matter.  (Ask me how I know this…).    Keep eliminating possibilities, and you’ll get there.

 

 

[Guest]

Are you using the tickler (T, Titillateur in your diagram) before you prime the motor?

 

On my both my brass singles ( Le Zèbre and Sizaire et Naudin) I hold down the tickler until fuel drips on the ground (about 5 seconds). Then I turn the choked engine over about 4 times with the ignition off. After that it usually starts first go.

[Akstraw]

I used this setup to diagnose a similar situation on a 2 cylinder Maxwell.  I took a short piece of angle iron, drilled and threaded for two spark plugs (modern plugs will do) and bolted it to the engine block.  Then removed the plugs from the engine, and connected the wires to the test assembly (upper right of attached photo, at about 2 o’clock).  Then I put masking tape on the flywheel and taped a paper TDC reference to the frame so I could mark results. (foreground).  With the plugs removed from the cylinders, I could easily turn the engine with the crank and see (and mark) precisely when each spark was occurring.  Another helpful device was a compression “whistler” (the green thing on the left side) which, when screwed into the spark plug hole, ‘whistles’ during the compression stroke, so you know exactly when that is occurring.   I found this a simple and useful way to absolutely confirm spark, ignition timing, and valve timing.

 

 

[MochetVelo]

I've used the priming cups to no effect. Starting fluid sprayed into the carburetor intake also doesn't work (though I haven't tried it directly into the spark plug holes). The flywheel isn't accessible, so Renault has a special way to time the ignition: An access hole directly atop cylinder #1 allows a rod to drop onto the piston that is marked with TDC and 8mm before TDC, the latter being the spark. I used that to set the timing. The plugs are sparking just before TDC on the compression stroke, judging from the valves. With the carb removed, a hand on the intake manifold hole feels strong suction when cranking. With the carb screwed on, I get much lower suction on it's intake, however. I still think the carb is not sending gas to the engine. Wish I had a similar carb to test on the car.

 

Phil

[Mark Shaw]

On 5/17/2022 at 6:05 PM, MochetVelo said:

a hand on the intake manifold hole feels strong suction when cranking.

A finger over the spark plug hole is your best measure to determine the compression stroke.  Why are you testing vacuum?

[Bob McAnlis]

Phil

my AX is the easiest starting car I have.    Original carburetor is preferred.  This engine runs hit,hit, skip, skip.    Not conventionally hit skip hit skip. 
 

yoi should be able to hear the fuel be sucked up into the engine.  Rotate the crank past one compression and stop before the next.  Give it a quarter flick up.   That’s all you need.    If you try to pull the crank before it’s the skip skip rotation it won’t start.   Good luck 

bob

[AHa]

Hey there,

Sounds like you have a fuel issue to me. I'd take the gas line loose at the carb to check for fuel flow. If you've got fuel there, and a good flow, then check to see if you can flood the engine. If by chocking the carb and turning over the engine, you cannot get gas on the spark plug, the problem is in the carb.

[MochetVelo]

I concluded your latter point as fuel was reaching the carb, but not the engine. This week, I got a correct original Renault carb and I am now working to install it.

 

Phil

 

55 minutes ago, AHa said:

Hey there,

Sounds like you have a fuel issue to me. I'd take the gas line loose at the carb to check for fuel flow. If you've got fuel there, and a good flow, then check to see if you can flood the engine. If by chocking the carb and turning over the engine, you cannot get gas on the spark plug, the problem is in the carb.

 

[MochetVelo]

I may have eliminated the question of the carburetor, as I replaced the Solex with an original Renault carburetor I was lucky to find. This is an original AX carb (or a very similar model), and it fits well. Anyway, the engine behave exactly as before. Not even a cough or sputter. It just seems like it is not gettig fuel. A test today might have brought me closer to the problem: With my friend's help, I cranked the engine with the muffler removed. Only a stubby tail pipe remains. But instead of air pressure coming out the tailpipe, we felt suction. The valves are seating and there is lash with the lifters, and they are sealing pretty good (I lapped them). It sounds like a leak between the exhaust and intake manifolds. My friend suggests I remove the carb,

seat the two intake valves and blow compressed air in tailpipe, then check for air coming out of carburetor intake hole. 

 

Phil

 

 

 

[edinmass]

Going back to your first post……….ran fine, then it didn’t. Good spark, lapped valves, ect.  Let’s face it, this isn’t rocket science. Compression, spark, fuel, and it runs. Tearing into and changing out components like the carb makes zero sense. This is a simple and basic engine. One which shouldn’t take more than a few minutes to figure out if it’s in correct timing. You keep digging deeper and disassembling things………without being insulting, it’s beyond you skill set. No shame there………experience is what you are lacking. Just find a talented pre war mechanic and have him look at it. I can’t imagine it would take more than half an hour to make it run. If it won’t fire on starting fluid and it has compression, it’s timing. It can’t be anything else. 

[MochetVelo]

I agree; it's probably a simple problem. The "new" carburetor is actually the correct one for this car. It was just pure luck that I found one a couple weeks ago. I had a similar "no-start" problem with my 1911 Hupmobile. It took forever to get it started, and then it only ran for a short time. I finally brought it to a shop. The problem was two of the spark plug wires were reversed.

 

Phil

[Terry Harper]

2 hours ago, MochetVelo said:

The problem was two of the spark plug wires were reversed.

A while back I made the mistake of installing a distributor 180 degrees out in a fairly large displacement six cylinder. When it did fire (once) it was rather impressive! I thought for sure I had blown the exhaust stack through the ceiling - the fire ball was rather impressive. With my ears still ringing I very, meekly and quietly re-installed the distributor in the correct orientation. Runs most excellent now!

Edited May 30, 2022 by Terry Harper (see edit history)

[Hemi Joel]

Did you check the ignition timing on BOTH cylinders?. Is it possible that you have The number one spark plug wire going to the number two cylinder and the number two spark plug wire going to the number one cylinder. It's easy to do by getting the two wires swapped around on the magneto. Or same result if the magneto, or the magneto gear is removed and improperly reinstalled.  If that is the case, you will have your spark properly timed on one cylinder, but the other cylinder will be way off.

So I am assuming that on one of the cylinders you have slowly cranked over the motor with the spark plug removed, hooked to the spark plug wire, and laying on the block, and your thumb over the spark plug hole. As you see that both valves are closed and you feel the compression stop building with your thumb, you get a spark.

What I am suggesting is follow the same process for the other cylinder to make sure that they are not reversed.

Edited May 30, 2022 by Hemi Joel (see edit history)

[MochetVelo]

On this car, the wire to no. 1 cylinder is too short to reach no. 2. I keep looking at stuff like that, though!

 

Phil

[Hemi Joel]

It could still be ruined like that if the magneto rest was positioned wrong . At this point you are stumped by thinking about what it could possibly be. I would quit thinking about it and check the timing of both cylinders just to be sure. I would quit using reason to determine what is or isn't wrong, and methodically check everything regardless of whether I think that could be the problem or not.

Edited May 30, 2022 by Hemi Joel (see edit history)

[Oldtech]

At this point anything is possible. Check first the camshaft timing, then the magneto timing so you KNOW that the spark is occurring at TDC  compression stroke. After that there is only Fuel. 

[Restorer32]

Has to be timing.

[MochetVelo]

27 minutes ago, Restorer32 said:

Has to be timing.

I've sure looked at the timing a few times. I have the spark set at 8mm before TDC, as suggested in the Renault manual. It does behave as though the timing is off, however.  Yesterday, I got one explosion, but it came out the carb. I also got two kickbacks. 

 

Phil

[1906 lozier]

are you sure that the timing is suppose to be before top dead center?  I have only worked on one car that way,  a 1911  Franklin,  all other cars are ATDC by about 8mm or 1/4 of a inch. I would change the timing to ATC and see what happens then. being you had a explosion out of the carb, that tells me it is sparking before the piston goes over top dead center,  than after it is running, then advance to 8mm before top dead center. being you have a kick back...too far advanced at idle.

Harold III

[MochetVelo]

I'll try that to see what happens. This is a non-adjustable magneto, however. There is no spark control while the engine is running.

 

Phil

 

37 minutes ago, 1906 lozier said:

are you sure that the timing is suppose to be before top dead center?  I have only worked on one car that way,  a 1911  Franklin,  all other cars are ATDC by about 8mm or 1/4 of a inch. I would change the timing to ATC and see what happens then. being you had a explosion out of the carb, that tells me it is sparking before the piston goes over top dead center,  than after it is running, then advance to 8mm before top dead center. being you have a kick back...too far advanced at idle.

Harold III

 

[edinmass]

Set the timing to fire one degree PAST top dead center........or you will break your arm.........safety first.