runs like crap

[andrew]

Hi folks,

I have a SIIA, 2.25 petrol that is a practically daily driver that has run beautifully for more than 15 years, with normal attention, maintenance, and problems of course. A few months back it started backfiring, according to wifey, on deceleration (didn't happen for me). It got progressively worse though -- rough and uneven running, difficult starting (but always did), sputtering acceleration, seemed to be low(er) power.

Time for some attention, obviously, so:
- new plugs (gapped at .030")
- new plug wires and coil wire
- new condensor, points (gapped at .015"; checked with dwell meter, approx 51-55 degrees), & rotor
- new dist cap
- new fuel filter
- new fuel lines near carb (literally saw a leak spring up when working on carb!)
- made a new LT lead line from distributor to coil
- checked to see it was pumping gas to the carb (though hard to say how much is enough)
- took (Rochester) carb apart (several times...) and found some buildup in screen (hoped that was the problem!), all else looked fine to me (minor adjustment to float level)
- new oil breather hose and some other worn out PCV lines
- dynamic engine timing (more on that below)

I haven't touched:
- coil
- fuel pump
- anything beyond top side of distributor
- other fuel lines

Setting the timing has been a painful trial and error (all error so far). My truck has a timing marker on the crankshaft pulley, but unlike the helpful pictures in the green bible and elsewhere it has only 2 prongs. I assume the leftmost one is 3 deg BTDC and the right one is TDC. I use 87 octane (always have) and have an 8:1 head. According to the gospel of others, my timing should be TDC or so.

After going on a scavenger hunt for the nearly invisible mark on the pulley, I used a timing light to adjust things. Set it up at TDC...no fun. 3 deg BTDC...no fun. About 3 deg ATDC (estimated)...no fun. By ear, ignoring the marks...no fun. In all cases it continues to run roughly -- more specifically, I can get it to run ok after very warm and on idle (at about 775 RPM), as well as when I drive about town AFTER it's fully warmed up. But if I try to start it cold it sputters, chugs, throws fits, and basically fights against me until fully warmed up. Then, it's basically ok (at TDC-ish setting). It never was so temperamental before, though. One thing I did notice is that with the timing light on it if I rev to about 2500 or so RPMs the timing mark wanders quite a lot (maybe 3 inches to the left as facing the engine; about 39 degrees according to the advance setting on the timing light, which I adjusted to get the mark back to the original one at idle speed -- I don't actually know if that makes sense, but it felt like an intuitively correct way to quantify the "wander"). I don't know if that is normal or if that indicates worn weights/springs? I'm out of my league on that one and am only throwing out a guess here...

So, if anyone has any ideas of what I try next, I'm all ears. I really appreciate any help or opinions anyone has to offer.

Thanks.

[ignotus]

Andrew,

You don't say how many miles on the motor but my guess is the timing chain/gears and tensioner need replacing. Heck, you've done everthing else! Like every thing else the timing chain and gears wear out. If your going in there do everything at once then you won't worry about it for another 15 years ;^)

gene

PS, great description!

[andrew]

The motor has about 15k miles on it since a rebuild (refurbished engine from our hosts). It has been leaking coolant from the front (one problem at a time!), which I suppose might be related -- my guess about that was water pump/gasket.

[artpeck]

Interesting problem. A few questions. Have you checked compression in each cylinder cold and hot? Might be a valve or head gasket issue and at least you could start localizing. What state are the plug tips in? Sooty, white, brown? Might also be worth pulling the pick up tube in the tank to see if there is weird blockage or the glass bowl...same thing. Also have you confirmed solid spark to each cylinder by pulling the plug wire and using as screw driver to arc it? I feel like you are at the stage of needing to eliminate stuff starting with fuel versus ignition versus mechanical per the post above.

[andrew]

I have not checked compression. When I replaced the plugs the tips looked perfect (light grey, no carbon or burning, not wet). Each cylinder is getting spark. My next instinct is to go to the fuel pump and/or the tank pickup to make sure it's getting sufficient fuel (seems like starvation at some level). Any thoughts on whether the wandering timing mark mentioned above is a concern or not?

[Les Parker]

Have you checked the vac advance on the distributor? Fit either a vac. pump to the line from the carb. or suck on the line to see if the base plate on the distributor moves. It could well be a vac. diaphragm that has perforated.

2p

[PavementEnds]

I second Les' suggestion. You should also check the retaining collar at the base of the distributor to make sure that both the retaining bolt and pinch bolt are tight. I once found that my pinch bolt had sheared in half -- still together enough to not show an obvious break, but broken enough to no longer do its job. In addition, I suggest that you use a vacuum gauge to set the timing -- it is slick! See http://sbftech.com/index.php/topic,3020.0.html I use the Mityvac.

[andrew]

Just checked it and, yes, sucking on the line from the carb does rotate the distributor base plate. And, the retaining/pinch bolt holding the distributor in place are solid (I've tightened them enough in the last few days!).

[mearstrae]

Maybe just try checking the vac. overall, for leaks or possibly a valve problem (may only need adjusted). The toughest problems often have the simplest solution.

'95 R.R.C. Lwb
'76 Series III Hybrid 109
'70 Rover 3500S

[artpeck]

Maybe I missed it but does it idle rough? I would check fuel starvation. It's not rich or you would have fouled plugs. And since the plugs are all the same and you are getting a solid spark it isn't likely to be an ignition issue. As a side bar are you sure the ignition wires are properly connected to each cylinder in the right order? Otherwise it feels like a fuel flow or carb issue. Even as easy as a failed carb gasket or other air leak or something blocking fuel flow. Back firing which you mentioned is from running lean and or over advanced timing generally speaking. At least you seem to be narrowing it down.

[artpeck]

One other thought. No idea what your fuel lines are but recently I had to replace a section on a piece of equipment where the line had delaminated and internally ballooned. Took me a long time and process of elimination to find the blockage. I would make sure your lines from tank to pump and pump to carb are free. And have you checked the sediment bowl and filter on the pump?

[andrew]

I don't see any vacuum system leaks.

It is difficult to start but idles ok, better when warm. It's under acceleration that things really start to be a problem.

The ignition wires are in the right places (from memory: 1, 3, 4, 2 going counterclockwise from #1, which is at about 2 o'clock if I stand on the passenger side of the car, looking toward the distributor).

Carb gaskets appear ok, certainly not leaking air or fuel as far as I can tell.

When I checked to see if it was pumping fuel, I disconnected at the carb and cranked -- it got gas, not gushing, but a flow...don't know what's normal, though. Sediment bowl appears clear, did not yet check the pump on the filter (though replaced the inline filter near the carb). I have not disconnected and checked all of the fuel lines so the possibility of a blockage (esp. internally) is there.

Thanks for all the feedback, everyone, keep it coming, please...

[busboy]

My initial thought is its not getting enough gas, is your inline fuel filter before the sediment bowl? Pumps always push way better than pull so perhaps that's a problem. Is your gas fresh gas, for many years I would leave mine sit then it would run rough (old gas) so now I only party fill so there is always room to top up with fresh if it starts running poor. Gas today is not what it used to be and for small engines I only use premium gas. Do you have an oil bath air cleaner if so 5W30? or is the paper element clean? You seem to have covered a lot of stuff already.

[andrew]

Inline filter is just before the carb, after the fuel pump. Gas is fresh and since I drive it so much--with such poor gas mileage--it never gets old. I have an oil bath air cleaner, which is freshly cleaned.

[CKubinec]

It is interesting. I have run across simular problems and often it comes down to a vacuum leak. It may not be obvious. Spraying the manifold and carburator gaskets with carb cleaner usually shows something. If it has power brakes pinch off the vacuum hose to see if things change. If you have a PCV valve use your finger to block it's opening briefly to see if it makes a big difference. A small change at the PCV valve is OK. I have had brand new PCV valves be bad. Good luck!!

[SafeAirOne]

I would say that the variable ignition timing at idle will be a prime concern. If you aren't able to nail down the timing using a few conventional methods, something's wrong.

I'd check the security/gap of the points, the integrity of the centrifugal advance springs and weights, the function and integrity of the vacuum advance system and mechanism AND, since almost ALL of the brand new capacitors are crap, I'd also replace the capacitor just because. Probably try to source a GOOD capacitor from from Advanced Distributors (http://www.advanceddistributors.com/index.htm). Though I have no distributor on my engine, I've heard nothing but good things about them, their distributor rebuilds and their capacitors.

Might also check for excessive play in the distributor and shaft.

Compression check is also in order, though I don't think It'll reveal a cause for your problem, personally. Maybe throw a vacuum gauge on there as well. Check for vacuum leaks while you're at it. Check for malfunctioning choke too.

Anyhow...that's the tack I'd take initially. It just boils down to the old fire triangle; fuel, oxygen and an ignition source.

[EDIT:] Wow--missed a whole other page of replies. Apologies for the duplicate recommendations en masse. I think the Advanced Distributors (http://www.advanceddistributors.com/index.htm) recommendation is original though...

[jonnyc]

I had similar problems, not exact - but close, and got many of the suggestions below. After fixing most of the relevant items, problems persisted. One guy suggested that I should check/adjust my valves. Well, one rocker was apparently out just enough to cause me all sorts of grief. If you haven't adjusted your valves in 15,000 miles, it might be worth a shot.
My SerIII is currently running like a champ.

[Billy5]

Funny, I have the same timing pointer and its been driving me nuts too. I am relatively new, but I could not but wonder about your timing. If i am not mistaken, which I very well could be, when you throttle up the timing mark on the pulley will move away from the pointer, to the left as you say. This is advancement, I do believe. Now did you throttle up, then set timing according to the advanced location on the pulley? If so, then your timing is off I would think. What I did was set my light to 0. Then rotated dizzy until pulley mark lined up with the first pointer which is zero. Then I adjusted. I found 12 degrees BTDC is good. I cant help with the carb as I got a Weber 32/36.

[andrew]

Adjusting the valves seems a good idea -- I'll do that and see (and report) if it helps. As for the timing, I set it at idle (about 775 RPM) at TDC (and other settings I tried, as mentioned). After setting the timing in this manner, I throttle up and the mark will move off to the left (facing the engine from the front of the truck). I believe that it's supposed to stay relatively constant throughout acceleration, though, which I believe is the job of the centrifugal advance springs and weights in the distributor, but that's really beyond my knowledge -- can someone clarify if that's the case for me? And, how do I check if the springs/weights are working properly? And what to do if they are not?

[SafeAirOne]

I don't believe that the purpose of the centrifugal weights and return springs is to keep the timing constant through acceleration...the purpose of the centrifugal advance is to advance the timing as the rotational speed of the distributor shaft increases (as engine RPM increases, in other words).

The faster the distributor shaft rotates, the more the hinged weights want to spread apart and away from center. The weights are mechanically connected to the 'floating' distributor plate (that the points are attached to) so that as the weights spread apart, the relationship between the cam follower on the points and the cam on the spinning distributor shaft change, altering the moment when the points open and therefore the ignition timing.

You should see a rising advance angle as RPM increases within the mechanical limits of the centrifugal system. The vacuum advance does essentially the same except based on amount of vacuum and generally kicks in after the mechanical limits of the centrifugal system, AFAIK.


See: http://en.wikipedia.org/wiki/Ignition_timing#Mechanical_timing_advance

[andrew]

Unfortunately, it's not the valves -- I adjusted the valves today and it's still exhibiting all of the bad symptoms. I'll do a compression check soon.

Next up is the fuel pump and lines, I suppose. It just seems like uneven fuel to me...

Any other thoughts?

[jonnyc]

OK, one thing before I did the valves was to seal every possible vacuum leak spot. I took both manifolds off and dismantled everything between the head and the brake booster, including my Rochester. Every joint got sealer, new gaskets (or both), new hoses & clamps. It didn't solve every problem, but it sure helped, and it eliminated vac leaks from the equation. That's what narrowed my issues down to the valves. Eliminate as many problem areas as you can.

[busboy]

Unfortunately, it's not the valves -- I adjusted the valves today and it's still exhibiting all of the bad symptoms. I'll do a compression check soon.

Next up is the fuel pump and lines, I suppose. It just seems like uneven fuel to me...

Any other thoughts?
Throw a fuel pump at it, if that's not it then you'll have a spare for trouble shooting next time. Make sure the lines are tight on the pump.

[Les Parker]

I would second the thought of a new fuel pump. Ethanol plays havoc with fuel pump diaphragms. :)

[bugeye88]

Speaking of fuel pumps, I've found an in-line low pressure electric fuel pump in-between the standard fuel pump and the Carb with an on-off switch inside the cab helps prime and fill the float bowels in the carb for easy starting and can serve as the pump if the diaphragm fails on the mechanical pump. Also use one of the many ethanol conditioning products out there to treat your gas and prevent ethanol damage to various parts of our Landy's. This goes for any older car as the rubber used on them does not hold up well to ethanol.
Motor On,
Bugeye88

[andrew]

I hate threads that I look up that have no closure, so here it is:

My next steps were to check the compression (great, by the way -- 170 plus or minus 5 across the board) and add a new fuel pump. I also blew out all the gas lines with compressed air while I was at it. No change really. Unrelatedly, I added a new water pump (had been developing a slow leak for some time), hoses, thermostat, belt, and heater control valve (broke upon removal of the hose).

None of this really helped or mattered very much. So, at this point I've replaced nearly everything that might have reasonably caused the problem. A lot of it I was going to replace anyway as maintenance (points, plugs, condenser, plug wires, water pump, belt; and valve adjust) so that was no big deal, but some was a shot at a fix that I apparently didn't need (fuel pump, etc.).

So...I said screw the specs I'm timing this thing by ear. Recall that I was at or around TDC (8:1 head)...I rotated until it sounded strong. Drove it for awhile. If it backfired I backed it off. If it was good I moved it more to see if it got worse or better. I always drove between adjustments until it was warm. After a bit of trial and error I settled in on a happy place. The truck sounds wonderful now and runs great again. I haven't pulled out the ignition light to see what the final number is but I'm guessing I'm at about 8-12 degrees BTDC, which seems way out of wack from where it's "supposed" to be. Oh well, screw it, it's quite happy.

I'll drive it, keep an eye on the temperature (see if it continues to run cool, so far so good) and the points (see if it burns through them), but I think it's resolved. It truly is running great (and so quiet with the new water pump and valve adjust!).

I guess the only question I have is whether it's possible that the crankshaft pulley was installed with the mark in the wrong place, or if it could have slipped/moved over time... I just can't imagine how else I could be running so well so far off the supposedly "correct" timing.

Happy driving.

[ArlowCT]

Sounds like you found your fix! I know every time I try using the timing light it never works and I always resort to my ear.

[stomper]

I am running at about 12 BTDC and that is where my engine is happiest. With ethanol in the fuel, you can't go by the book specs.

[Revtor]

On my the engine, the crank pulley has one tick mark and then the pointer has two points which basically get you around 0 degrees. So when you actually time it to run right, the markings really don't help because there are none out by where it's happy! (Unless I'm doin' it wrong) Time, check for detonation, tune, check, tune, check etc... you got it.


glad you figured it out..

~Steve

[stomper]

I have a few timing marks on my crank pulley, but like Steve, there are no marks out that far. That's why I said about" 12 degrees BTDC. :thumb-up:

[albersj51]

When Advance Distributors rebuilt my 25D he recommended I set it to 12-14 degrees BTDC. So I don't think you're that far out.

[bobzinak]

It's good that you figured out your problem (for now). one of the many things that has happened to me was that there is a small machined part that is under the triangular distributor, that holds the clamping bolt. it converts the distributor drive to the offste slot for the distributor base. many have put ti in 180 off, which makes you distributor 180 degrees out. I am thinking that the initial drive gear off the cam might be used for the diesel moters too. the piece has two flags that stick out to fit in the slot on the drive gear, the other end has the offset slot for the distributor. in my case one of the flags had broken off and allowed the diatributor to change the timing dramatically. I thought it was the dist. even took it in to have it tested. pain in the a**.
the other item concerns the timing chain. they stretch.. some tomes alot. and the timing chain tightener would not go into the next slot on the saw tooth arm that hold the chain tight. you could see it had room to move to the next position, but would not go past the key on the arm to fall in the next postion. a sharp blow with a hammer and piect of wood did it...sometimes. it got to the point that the timing chain had so much slack that it started rubbing in the timing chain cover.
also, if/when you ever remove you front cover, you may notice that the caam gear has several slots you you can put the cam gear on and change its position relative to the cam. as you timing chain stretches it will change cam timing, and so performance. you can see how much it is off by where the cam gear points to the stud on the block. by rotating the gear you can put it on in one of the other slots on the cam gear to compensate for chain stretching. (not all cam gears have multiple slots, some just have one). htis is just to let you know that your loss of power may be related to timing chain stretch, and may just need reallignment to improve power output from you engine. Hope this helps, just a thought from me, I've owned my s11a for over forty years and have just about every part in my hand, many more than once..owing a land rover is more of a hobby than amode of transportation. I think its like having a bi-polar girlfriend, when she's happy it all good, but that can change very quickly. a rover will make you alot of friends. just remember. it's only a rover...rove on my friends. bobzinak

[singingcamel]

What kind of carb are you using ?, zenith carbs are notorious for warpage at the base , screwing uo the air fuel mixture. but my bet is a vaccum leak.

[andrew]

Rochester carb, in good shape.