Smart engine - It LIVES!!!

[Crazymanneil]

Cheers Nanko. I had thought it would be hard to warp the head although it may be possible. The leaking injector initally put the engine through quite a lot (injecting fuel on exhaust stroke and very advanced timing!)

I am thinking also that perhaps the leaking injector I had before washed oil off the bore causing piston ring/bore wear. This may let oil past and cause the symptoms I am getting. However a friend pointed out that the compression would have the tendancy to push the oil towards the sump rather than into the cylinder. It does not explain lack of oil pressure though.

I would not know for sure without lifting the head. At that point though I think it would be best to get another engine as I have no manuals/gaskets etc for it.

Neil

[Nanko]

Hi Neil , if there was few CCM oil in the cilinder you must have noticed difficiculties when starting the engine . dead volume is very small and oil in the combustion chamber will increase compression.
Can you feel irregular resistance with pistons halfway, when turning the flywheel by hand ?
This could mean a damaged big end bearing causing low oil pressure
Hope my poor english makes sense

[Crazymanneil]

Nanko,

Thanks. No there was no difficulty starting engine to begin with. I also turned engine over by hand and it was fine too with no tight spots and good compression.

I am starting to think it may be head gasket as suggested by diesel dave. This would explain low oil pressure and blue smoke. I'll try it with water although I've started to look for another engine now.

Neil

[Nanko]

I'm following this thread with great interest , let us know what you see when the head is of.
Ofcourse I could be wrong , but I expect the problem is in the engine bottom , not in the top.

Did you try to run the engine with the cranckcase breather tubes disconnected ? increased cranckcase pressure can push oil into the combustion chamber ( as mentioned before )

[Crazymanneil]

Nanko,

Your previous post about crank bearing failure had made me think of the possibility of pressurised crankcase also. However the oil breather is currently not connected to anything and is hanging in the air. It is also not blocked because when I turned engine upside down to empty last bit of oil it came out the breather hose. I also tried opening oil filler cap with engine running to see if it made any difference but unfortunately no.

What I can say is -

1) Engine seems(or at least once!) to make oil pressure initially but then it drops.
2) Oil appears to be getting burnt as I am getting blue smoke.
3) Engine revs beyond throttle setting when this occurs.

To me the ways which oil could be getting burnt are -

1) Getting past piston rings
2) Getting past inlet valve oil seals
3) Head gasket

(2) seems unlikely to cause oil pressure loss as does (1) to be honest so to my mind most likely explanation is head gasket failure. Possibly due to combination of stress to engine by the faulty injector at the start and no coolant. Could anyone post a list of places that would cause oil pressure loss? I know camshaft bearings, big end bearings and head gasket would be likely culprits - any others?

It is also possible that the engine was like this to start with because I know I cannot trust the supplier anymore (who purposely puts a dead injector into an engine they are selling?!?!). I may name and shame them?

If I manage to get another engine I will definately take this one apart to see what the problem was and will post the info.

Neil

[Nanko]

Nanko,

Your previous post about crank bearing failure had made me think of the possibility of pressurised crankcase also. However the oil breather is currently not connected to anything and is hanging in the air. It is also not blocked because when I turned engine upside down to empty last bit of oil it came out the breather hose. I also tried opening oil filler cap with engine running to see if it made any difference but unfortunately no.


Could anyone post a list of places that would cause oil pressure loss? I know camshaft bearings, big end bearings and head gasket would be likely culprits - any others?

Damaged oilpump , erratic oilpressure switch , faulty oil pressure regulator.

IMHO leaking head gasket is unlikely , around the cilinder bore you need lots of cooling liquid , there is no place for an oilbore , usually this bore is placed few cm from the cil.head edges , so the oil has to travel a big distance and have to cross cooling liquid bores.
Also if the leak is big enough to let the oilpressure drop ,it will effect compression ,I cannot imagine the oil circuit can take the 30 + Bar pressure so I dont think the engine would run on all cilinders

It is also possible that the engine was like this to start with because I know I cannot trust the supplier anymore

I tested engines the same way many times , and never had problems.
Aluminium is a good heatconductor , the heating proces is slow , so the temperature inside should follow to the outside temp close, and you would have noticed overtemperature
They probably sold you a damaged engine

If I manage to get another engine I will definately take this one apart to see what the problem was and will post the info.

Neil

[Crazymanneil]

Nanko,

Thanks for the input. It is a good point you make that the compression would be high for the oil to be entering the cylinder although I have seen water enter the cylinder on a VW TDI and eventually cause hydraulic locking.

I also tried filling the engine with water (no pump). Engine ran as normal initally (with oil pressure ok) but then did same thing again in more or less the same time. Either it takes time for the oil to work its way to wherever its getting into the cylinders or else it is heat related. I did note however that there was no oil in the water and smoke was approx same colour as before.

So I am resigned to stripping the engine now to find out what happened. Before I do this I want to try a few more things to get some more clues. I think I will change the oil for heavier stuff (normal is 5w40) to see if it makes any difference. I will also try taking exhaust manifold off again to see if smoke comes from all cylinders or only one (narrows search when engine is apart). Any other things I should find out before stripdown?

I think your last comment that the engine was probably already damaged is the most likely. I think that because I bought it from a breaker in Germany they must have given me the worst one they had thinking there would be no comeback. I have already found the faulty injector which someone *must* have known about so perhaps this was a "spare parts engine" they had for a while. Its frustrating that its taken so much time as well as the money. I suppose that I have learnt a lot though!

Neil

[johnfireball]

Hi.
Have you checked the oil feed to the turbo as perhaps its allowing oil to flow straight through and back to the sump so causing low oil pressure.My diesel has a sensor in the water jacket which enrichens the mixture when the engine is cold and shuts off when the water heats up, perhaps you need to plumb it up properly and run it up to temperature after fixing the oil pressure problem before pulling it apart as gaskets etc cost a small fortune. If its not the turbo oil supply causing the low pressure problem I would firstly fit a gauge in place of the sensor to get a true reading next change the oil filter and if no change I would then remove the sump and check the oil pump strainer the oil pump itself and then the oil pump relief valve. Some turbo engines have nozzles that spray oil to the undersides of the pistons to take the heat away and there may be a problem with this system. Plus with the sump off you can check the main and big end bearings. If you are careful removing the sump you can probably reuse the gasket.
John.

[Crazymanneil]

You make some good points John. I will take these on board and go after the oil pressure problem in that order. I am actually wondering if I have 2 problems with the engine and am allowing myself to believe that one is related to the other. If for example I had another dodgy injector that could cause the engine to rev up and possibly some blue smoke due to bore washing. And the oil pressure would be a totally separate issue to that, possibly oil pressure switch. Must get a gauge!

I don't think turbo is leaking, at least at the oil feed union. The oil return seems to have leaked a little (talking a light smear here) from being unbolted before.

I also think the sump is sealed on with liquid type stuff rather than a gasket. In fact most of the engine seems to be that way except for the head gasket of course.

A quick query. I'm going to take the turbo off tomorrow )to look at the smoke coming out of each port). If I blocked off the oil feed pipe to turbo completely (using a bolt or something in the banjo union) would this cause oil pressure to rise too much / break the oil pump? When I ran the engine before with the turbo off, I put a pipe over the end and routed the oil to a tank (and the floor!). I was worried about blocking it off completely so went that route but blocking it would be much easier.

Neil

[Nanko]

When I ran the engine before with the turbo off, I put a pipe over the end and routed the oil to a tank (and the floor!). I was worried about blocking it off completely so went that route but blocking it would be much easier.

Neil

There must be a pressure regulator somewhere in the oil circuit.
Oil quantity delivered by the pump varies with the engine rpm and
oil viscosity
To maintain a constant oil pressure the overcapacity of the pump
is dumped into the sump.
So , as far as I can see its safe to block the oilfeed to the turbo

[Crazymanneil]

I'm thinking that too Nanko. I've never gone into any real detail of oil circuits before now although did some reading yesterday and what you said about oil relief valve makes sense. Will poke some more at this thing...

Neil

[smokyjoe]

Sorry to hear about your Smart problems, having to deal with the engine was the last thing you probably thought!

Maybe it's a stab in the dark, but I had bought a VW Diesel engine at a wrecker as a replacement for the tired original diesel in my car. It was in a pickup, and the junker used it in the yard to grab parts off other vehicles before I bought it, . It was run without an overflow tank so it had coolant just up to the head. I noticed oil in the coolant, but drove it for 200,000 miles before the head gasket finally went. The head was warped from the beginning, and the oil pressure feed to the head leaked a little to the outside of the head past the gasket but the pressure held up. When it finally went a lot of oil dumped into the coolant and the thing really leaked bad and burned lots of oil. But when cold, there was hardly a leak.

I'd rig up something to do a pressure check of the cylinders with the valves closed and see what's leaking, but sometimes these things are elusive and heat may be the factor opening up a leak. I think running without coolant would really warp the head, aluminum heads are unforgiving. But the damage quite possibly was done before you got the engine so I wouldn't blame myself.

[Crazymanneil]

Cheers smokey. I'll reserve judgement on whats the cause until I open the engine which is looking more and more likely. To me, the engine having the leaking injector at the start is the biggest clue that the rest of the engine is suspect.

Neil

[Crazymanneil]

The saga continues.

Took the turbo/exhaust manifold off again and put a bolt though the banjo union to stop oil leaking out. Still getting oil pressure at the very start and then it drops off to nothing. Also tested the oil pressure switch with a friend and found that to be working ok. This would indicate that oil pressure issue is heat related.

Number 2 cylinder had blue smoke. This had one of the new (to me) injectors that I bought in it so I swapped it for another one and got the same result. I wondered if the new injectors were faulty so swapped no 2 and no 3 injectors. I thought that this made the problem move to cylinder 3 so suspected all injectors dodgy. However, swapped again and played around and problem seemed to stay on cylinder 3. Then put the newer injectors in all cylinders to see what happened and smoke seemed to come from cylinder 2 or 3 although hard to tell.

This of course does not explain low oil pressure regardless, just thought I maybe have 2 problems (engine overspeed and low oil pressure). Overall it was difficult to draw any conclusions so I think its time for another engine. I will of course pull this one apart to see what is inside. I'm also tempted to get the injectors tested at about £20 each to see if the newer ones are ok or not.

Once engine is apart if I find anything I'll post some pics. Cheers for reading.

Neil

[Crazymanneil]

Hey,

Just a note to say I am still plugging away with this engine. I sorted the low oil pressure due to a tip from Erik over at EVA. So now I am left with only 1 problem, that of the engine overspeed (and smoke).

Having tried swapping injectors round I also got them tested although this revealed nothing except that the injectors appear to be ok. I have therefore started stripping the engine to see whats going on, hopefully get the head off tomorrow although information about this engine is hard to find in the UK unless anyone has any suggestions? Things I need to know about are how to set the camshaft timing and how to tension the chain etc. I guess I can figure these out although it would be better to read rather than reverse engineer.

Tested oil seals on valve stems by following some advice from Nanko. These also appear to be ok so its down to piston, head gasket or bore/piston rings. A second opinion from a couple of diesel fanatics (one who worked on trucks for a living) seemed to conclude that something is wrong on cylinder 3 and she's getting a small amount of oil. Once the engine is warm this oil is then able to burn and self sustain to some extent (eg when no 3 injector is unplugged). This adds to the combustion and increases the revs, but needs the kick from the diesel injection to get going.

Whatever's up with the engine may be terminal, but I'd like to know what it was for curiousity sake at least. As promised when I find something I'll post pictures.

Neil

[Diesel Dave]

Neil,

Simplest to fix will be that the ring gaps have lined up.

Failing this I'm betting in a cracked piston, or broken ring.

What do I win if I'm right?

Dave

[johnfireball]

Cracked head
Do I get the chocolates?

[andrewaust]

Interesting posts! Yep if an oil line goes down the head to feed cam bearings, maybe a cracked head is letting oil through into the cylinder, as this would happen as engine warms. Without looking at the engine and how oil galleries go through it, it would be hard to know. If the engine runs on the oil the crack most probably be on the inlet port side.

Cracked piston or rings etc, might be but it is firing on the cylinder OK by what is getting posted, its just so damn hard to say from text and not seeing the engine in real time.

Looking forward to the verdict

[Crazymanneil]

hmm

Head is off and nothing obvious other than a little 'dent' in the top of piston 2 and 3. (will take pic) This is either through heat from the bad injector or because the bad injector did not have copper washer (clearance). The dent is almost the same on 2 and 3 so its likely to be the clearance issue rather than heat because the bad injector was only in cylinder 2 for a very short time. I'm not sure if this would cause the oil ingress to combustion chamber.

Nothing visible wrong with the head although might be worth getting it pressure tested. No noticible scratches etc in any of the bores. Putting my hand to the top of the pistons I can get them to move around a very small amount in the bores although all of them seem to be about the same, not sure if this is normal or not. The honing marks are still visible in all of the bores also.

The bores are set in such a way that they are completely surrounded by the water jacket. This to me means there is no way the issue could be head gasket failure or warped head because the engine would have at least put oil into the water which has not happened.

So oil is either getting by the rings or in via the inlet tract somehow (valve stem seals or cracked head) although valve stem seals did seem ok before. I put some spray oil into the bores and noted that it seeps past the rings on all cylinders so don't think thats much of a test. I think the only thing to do now is dismantle the bottom end unless any other things I should check?

I should correct a mistake in my previous post, it was in fact Nanko who gave the tip on valve stem checking. My brain is a bit frazzled!

Neil

[Crazymanneil]

Some pics here -

http://www.crazyprojects.com/engine/

The bottom end of the engine is stranger than I am used to so it was awkward to get the piston out but I got no3 out as in the pics. (the bottom end of the engine is all braced and baffled - to take apart properly would probably mean splitting the bottom end of the engine and removing the crankshaft also!)

The big end bearing shell pictured is from no3 piston which had the bad injector at the start. It was reassuring to see that it looks more or less ok since it took a right hammering, although you can be the judge of that! Conrod looks straight too. Piston rings look ok with no scores or bits missing.

Interestingly the conrods are made as one complete piece and then the bottom end is broken open, leaving a rough finish where the two parts bolt together (meaning it has to be the right way round!). I thought this was a BMW thing from the M3 but I guess its been adopted by others now.

Still pretty confused, nothing visibly wrong with the engine really other than the little dint in the top of the pistons. However, I can't see how that would lead to blue smoke and high revs at idle?

Only thing I can think to do at the moment is get the head pressure tested to see if thats the problem. I may also pull the other two pistons. Anything else?

Neil

[Nanko]

I put my money on a bad injector , leaky when engine gets warm.
It explains many (if not all) of the symptoms you mentioned

[Crazymanneil]

I put my money on a bad injector , leaky when engine gets warm.
It explains many (if not all) of the symptoms you mentioned

You might be onto something there Nanko. I was wondering the same thing myself. However I have 5 injectors (3 of them from ebay and supposedly are ok when removed). I have tried all these injectors in every combination I can think of and still same symptoms. That does not mean I don't have 3 bad injectors or even all bad injectors!

[oilburner]

To test for a bad injector, perhaps you can connect one of your spare injectors electrically to the electrical connector of a suspected bad injector. This would effectively disable the suspect injector but should trick the ECU into thinking everything is as it should be. The suspect injector wouldn't fire - it the smoke goes away you have found the problem.

[Crazymanneil]

To test for a bad injector, perhaps you can connect one of your spare injectors electrically to the electrical connector of a suspected bad injector. This would effectively disable the suspect injector but should trick the ECU into thinking everything is as it should be. The suspect injector wouldn't fire - it the smoke goes away you have found the problem.

Oilburner, I previously pulled the connection off an injector when the engine was behaving like this and it continued to do so. (the ecu will continue to run with 2 injectors). I reset the ecu and tried again with each of the different injectors and got the same result. Thats not to say that an injector is not doing something weird when the engine gets warm and is not dependent on the electrical connection...

Neil

[oldbmw]

years ago I had a diesel isuzu . the turbo developed a leaky bearing and from time to time the engine would overspeed fed bythe oil from the turbo going down the inlet tract. Is there any way a valve or breather could be allowing oil into the no 3 cylinder ?

[Crazymanneil]

Larry,

Thanks for the suggestion, but the turbo was actually completely removed from the engine (so that I could see if one exhaust port was smoking). In fact the turbo has not yet been connected to the inlet as I have yet to get the pipework organised. This also goes for the breather pipe.

Another thought I had - the little mark in the top of the piston could create a hot spot? Perhaps leading to precombustion? Just thinking out loud. I would have thought the reduced fuel injection should have compensated for it though.

ho hum

Neil

[Nanko]

Another thought I had - the little mark in the top of the piston could create a hot spot? Perhaps leading to precombustionNeil

Combustion starts at the moment of injection .
Only air is compressed ,there is no fuel .

[Crazymanneil]

Just an update for those wondering what the story is.

I think I have found the issue with the high engine speed. I tested the ECU on another engine and it did the same thing. Ran fine for a couple of minutes and then started revving up by itself. It seems to be related to running time but its the ECU that seems to be the issue rather than the engine.

The accompanying smoke seems to be a red herring. I have heard that these engines can be smokey for the first while of running and having the bad injector at the start cannot have helped. I am hoping that if it was given long enough to run it would sort itself out.

The ECU has therefore been sent back and I have ordered gaskets and head bolts to re-build the engine with (as I took it apart in desperation!). I just got word today that the gaskets have arrived so hopefully the engine goes back together easily enough as I have no manual for it.

I think the chain tensioner will be the biggest challenge as it is buried inside a side case which may have to come off to retension it (if there is a ratchet inside). I ordered a new chain tensioner regardless so I can see how it works before taking the side casing off. (side casing encloses oil pump and needs to be sealed with sealant so I want to avoid disturbing it if possible)

Neil

[andrewaust]

Hey thanks for the update Neil, well I'll be buggered , so the ECU was faulty, I bet you could kick the heck out of something when you found that out.

I've never rebuilt a smart engine, so I cannot help you with putting it back together, have a good look on the net, or even ebay might have a manual or DVD on the engine.



Cheers buddy!


A;)

[Crazymanneil]

Cheers Andrew,

To be honest I was just glad to get to the bottom of it (touches wood). It was also nice to know the internals of the engine seem ok even after the abuse it took from the bad injector.

Actually got a decent site from the guy in the Mercedes parts dept for anyone working on a merc -

http://www.service-and-parts.com

Might be of use to someone. Looks like the chain tensioner has no ratchet. The new one comes with a pin that you remove to allow the tensioner to push against the chain guide after installation. Hopefully play around with the one thats already in the engine and not have to take it all apart.

A friend at home suggested it was the ECU but then he also suggested everything else so was bound to get lucky. He's still taking the credit though

Ho hum, I'll get there.

Neil