Problem with my Petter. AVA

Hi everyone,
Im a new member, and I have a starting problem with my Petter AVA,the problem is that its not starting. Ive checked the injector, and that seems to be working fine. Ive also tried the usual cold start but wont even fire. What should I check next? Any help/ ideas would be appreciated.


Thanks,
David

I'm not a massive diesel expert, but one thing I do know, if there's any air been introduced into the system (IE, changed fuel filter, drained tank, taken anything off for any reason) these single cylinder diesels take a long time to bleed back in. I've had to bleed 2 diesel stationary engines in before, both times others around me thought there were problems with the engine, when there wasn't. It's just that such a tiny amount of fuel is pushed through, & not forgetting it only happens every other revolution, so it takes an age to get it through the pipes, much longer than you might think (I really can't emphasise that enough).

Even when you think it's through there's still likely to be a few air bubbles still to work out, which takes even more time.

Is there an oil squirter for cold starting? It probably needs 2 full squirts in this weather.

Anyway, that's about the limit of my helpfulness. Best of luck.

As Nuts says check for any air in the system. Are all the connections tight, are the fuel lines all clear, is the filter (if fitted) clean. You say the injector is ok how did you check it? Has the timing been altered?
If the fuel system is ok then the problem could be down to compression, this is how a diesel works it has to have good compression so the diesel gets hot enough to ignite.
You'll just have to check things and report back with your findings.

Stu.

Hi,
Thanks for both replies, Ive checked for air but injector seems to be fine, I haven't changed anything on it recently so I don't think any air could have got in. Whats puzzling me is that it wont even fire with plenty of cold start. Engine has worked fine for the last 10 years or so. It powers a saw bench and usually starts first swing.

Thanks
David

By cold start, do you mean Easy-Start, the stuff in a can that is reputed to kill engines?

It's not good for engines, I gather. They end up becoming dependant on the stuff. Some say it causes microscopical bending of the con rod over time, lowering the compression. Others say it breaks up the piston rings (especially the top compression ring).

Either way, it causes a small explosion inside the cylinder. So what? Isn't that what normally happens??? Well, no it isn't. It's supposed to be an internal combustion engine, not an internal explosion engine. Also, it cleans oil off the cylinder bore, which can cause damage to a cold engine.

I dunno how true all this is, but I prefer not to risk it myself. I have used it (sparingly) in the past, but usually it is only needed if there are problems with the engine (which there were in my case). A good engine, in working order, shouldn't ever need the stuff.

Does your engine have the cold start oil injector plunger on it somewhere? One which you lift out, fill up with engine oil from the squirt can, then push back in??? These are very effective. They squirt the oil into the inlet tract, right onto the inlet valve. This not only helps with compression by lubricating the upper cylinder, but also gives the engine something more to burn. My brother has a Petter AA1 with one on it, he swears by the thing. It should be filled twice in this really cold weather.
Maybe if you can get in there you should squire a good 2-4 squirts of oil from your can straight into the inlet tract, as close to the valve as you can get. This might help her spring into life.

Also, when you say the injector is fine, have you removed it, turned it round & turned the engine over, looking at the spray pattern? Was it spraying a good cloud of atomised diesel? No drips or squirts?

How's your compression?

Thanks for your reply Matt,yes I did mean easy start,aerosol,very difficult to start without it,for the last few years!I have removed the injector,spray pattern seems o.k.I have never seen an oil injector ,will look tomorrow.I am starting to think its a compression problem.
David.

You might want to try getting some oil in the barrel then, either by squirting it into the intake manifold as close to the inlet valve as possible, or even down the injector hole (I think these are direct injection).

It may restore the compression enough to get it started.

If you've been using Easy start for the last few years to start it I'd say it must be a compression issue, could be time for a strip down re-grind the valves and see what the bore and piston are like and re-place the piston rings.
Once it's rebuilt try your best to start it without using easy start and you can get the engine off it, it's the same as a drug addict.
Easy start is not a problem to use on the odd occasion, I've heard it bent a con. rod on start up as it had too much squirted in, the engine needs to be turning over before using it and it only needs a wiff of the stuff. Normally once the engine is overhauled and back to it best you can get them off easy start.

Stu.

HaHa,success!thanks for the tip with the oil,managed to get a couple of squirts a log way into air intake,she fired up after three attempts,I guess after the bore was coated with the oil.Now I have to think about stripping down,never attempted anything like this before is this difficult?What order is it done?Sorry for all the questions,I'm not that confidant I will manage to get it all back together!
David

It's a little bit more involved with diesels. If it's a single cylinder that makes it easier.

Basically the head & barrel gaskets could well be solid metal, & there may well be more than one of each, these act as shims to make sure the gap between the top of the piston & the face of the head is exactly right.

The correct way to rebuild this is to do a "bump-gap test", usually performed with strips of lead or solder & the head & barrel have to be torqued down, tested, undone whilst the material is removed & the gap measured, then shimmed up as the manual dictates. But in most cases as long as it goes back together as it came apart it should be fine.

You might want to see how you get on with it. If it carries on starting & running satisfactorily with the oil trick then there may be no need to strip it down. Personally I would strip it down, but that's because I am addicted to taking engines apart, I am not working at the moment & have little else to do with my time. If it runs & starts OK (without any easy start) then it may well be OK.

If you want to strip it down there'll be plenty of help here. Whereabouts are you? There may be someone nearby who's willing to help.

Thanks,I think I would like to rebuild ,when snow situation improves.It is a single cylinder and I am in Sheffield,if anyone can spare any time plenty of tea,coffee,buns supplied
David

Sorry your a bit to far for me to travel to help. When you strip it down try to lay the parts in order, take lots of pics, write down anything that's a bit complicated, label parts and keep nuts and bolts seperate so you know what goes where. Thing is once you get the head off you can check the bore, if this is worn you'll have to think about what you want to do with it as it might not be worth repairing if you need to buy all new parts as I don't think there cheap.

Stu.

Yep, strip it down, lap the valves, check the bore/hone it and check the ring gaps.

RE Easy start, this one always makes me laugh, engines don't get addicted to the stuff!!! lol
If you need to use easy start to get an engine running, there is a problem. By using easy start, if it starts then you have simply "stepped over" the problem, over time being un-fixed the pre existing problem just gets worse giving the illusion that the engine only wants to start using easy start.
Often if a diesel is slightly down on compression easy start will get it going for the first crucial couple of thumps, providing that little extra heat and momentum to let the diesel ignite afterwards. In the mean time you still have an unresolved compression issue that is only going to get worse until it is addressed one way or another.

Personally I only use it for diagnostic on petrol's, a small wiff of the stuff to see if she fires then in most cases on to clear the idle circuit on the carb

I know what you mean Blackvanman (it's Andy, isn't it? I think I called you something completely different on one of my early threads ) but I still think Easy Start can cause an engine damage if used for prolonged periods.

However, on my dad's old barge he had a John Deere Shire 4.5 litre 4 cylinder diesel engine. These had no cold start facility & in the book they told you to use easy start in really cold weather, which is why I've got a can of the stuff in the workshop (my dad gave it to me because it has a picture of a BMW car on the front, he thought that was funny ), but I guess using it in "very cold weather" doesn't constitute prolonged use. Had the engine been destined for colder climes no doubt it would've had a cold start facility fitted.

Would be interested to know what damage it does, if any. Strange how this engine sprang into life with a little engine oil down the barrel. Surely if easy start does that much damage then it would still be a non-runner.

I guess we'll find out if/when it get's a strip down.

Still, the fact remains, these engines were designed to run on diesel, not ether (or whatever goes into a can of easy start). I use mine for much the same purpose as Blackvanman does, simply to get something running in order to diagnose other problems, & always very sparingly.

David, if you do decide to strip this engine down, you'll find plenty of help here. Just make sure, as Stu says, to take plenty of pictures & keep things noted down. I collect jam jars & plastic pots/tubs with lids for all my engine restorations. I keep all the various nuts & bolts from different areas of the engine in these pots. I usually scrub them all in parts wash before reassembly, but that's a bit too far for most people (I've got plenty of time on my hands).

It's easy enough to get a few jam jars together, even margarine tubs will do, although you can buy cheap plastic tubs with lids from pound shops or cheap household/kitchen type shops. Anything like that will do, but stuff with lids is always better, unless you're careful (you can bet one or two will go flying off the bench with a knock from an elbow or something at some point).

Best of luck whatever you decide.

Thanks for your thoughts guys,I will update as soon as I start the rebuild,I'm positive I'll need your help then!
David