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Another Engine Smoking Thread


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23 replies to this topic

#1
trogboy

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I have spent the last hour or so searching the millions of threads on smoking engines but haven't found what I'm looking for so bear with me a minute.

I have just finished building and installing my hybrid TU engine (TU24 top end with TU3 bottom end). I spent a while trying to get it to idle at all (maybe 30 mins of engine running time in total) but had no success so I decided to take it to a local specialist to have a look at the carbs. To begin with the exhaust was full of condensation then it went clear. Just before I packed it in it has started to puff out blue smoke which I thought was related to the fact that I had gradually been working out the mixture screws to try and get an idle.

I've just spoken with him and he says that has changed the idle jets as he says the originals were much too lean so he couldnt get an idle. He also says that the engine is now permanently puffing blue smoke even though he has got the emissions right!

The bottom end was brand new as a TU3S engine had been bought in error by a Citroen garage in St Helens and I picked it up as obsolete stock for a song. I think it is about 18 months old but has never been fitted. The parts guy said he had been turning it over by hand regularly as he had his eye on it for his own car.

The head/valves have been checked over by a couple of people, including Matt at QEP and has been pronounced good. I fitted brand new oil stem seals from Peugeot to the head about 12 months ago (last time I had a go at building an engine with it) since when it has probably run for a couple of hours max. The head has spent quite some time sitting on the bench over the past year though.

The guy doing the work said after he sorted out my idling problem he changed the oil as the stuff I had put in was now as thin as water and stank of petrol - the engine is still smoking though!

He's a bit baffled (as am I) but he suggested that the engine may stop smoking as much once it is bedded in. Surely that can't be right?

Compression was good and even across all cylinders before I left it with him so I suggested a leak down test to check the rings but he seems to think that will only tell me if the compression rings are shot and not if it is the oil control rings are gone, which is presumably what I need to know.

I take it that it's not normal for TU engines to have a smoking habit when new?

p.s. sorry for the long post

#2
axnutty

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The guy doing the work said after he sorted out my idling problem he changed the oil as the stuff I had put in was now as thin as water and stank of petrol - the engine is still smoking though!


I take it he's put in the right oil? Why was your existing oil no good and full of fuel?


I take it that it's not normal for TU engines to have a smoking habit when new?


No


I cant see the engine wearing out that quickly unless there was some issue with the oil system itself. (Given its as good as you say it is.)

#3
stu_woac

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my build has never smoked apart from black LOL #

even when first build,, something isnt right here,, What head gasket did you use?? also your using twin 40s right?? so the oil breather isnt a issue,

you say the guy turn the lump over by hand I take it he had the head on it as turning it over with out moves the liners

#4
steve@cornwall

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Firstly, I know nowt about carb installations, so guess-work time, what I'd think if it were mine! (I've had plenty overfuelling gtis)

when you first built it , it ran, albeit badly, without smoke and "Way too lean"

Guy fits bigger jets and it runs better but has fuel in the oil and smokes blue (or could this be grey smoke?)-both signs of overfuelling! so I would deduce the jets were oversize?

I'm assuming that a speciallist changing fuelled oil also flushed and changed the filter.....removing all traces of petrol. I've noticed just changing the oil isn't enough.

#5
Sandy

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I expect it's an issue with the stem seals or guide wear.

#6
trogboy

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AXnutty - I'm guessing he put in the correct oil but to be honest I forgot to ask. He thought that the oil was contaminated because of the possible over fuelling whilst I was trying to set it up myself. I could only get it to run by screwing in the throttle stop so far that it was running on the main circuit.

Philip - I used a Payen? TU3/TU24 head gasket (it is the same part no) and yes I am using twin 40s. At the moment the breather is running to a separate filter rather than back into the air intake system. The parts guy from the Citroen garage used to turn it over by hand whilst it was there but the TU3S engine was complete at the time. I only ever turned it over with liner clamps in place when I had the head off so Im not worried about any of the liners having been disturbed.

Steve - It ran to begin with but only on throttle so I kept winding out the mixture screws to richen the idle mixture but I still couldn't effect an idle. After a while it began to smoke so figuring it was now way too rich I leaned it all back off again and gave up :) He thinks the fuel in the oil probably came from me running it too rich and perhaps getting a bit of bore wash. I was having to pump the throttle a bit to get it up and running so there was probably plenty of excess fuel involved. He definitely changed the oil and the filter but I'm not sure if he flushed the engine through.

Sandy - Matt seemed pretty confident that there wasn't excessive play in the valves and the oil seals have only covered about 2 hours use max since being fitted to the head a year ago at which time they were OE from Peugeot. I thought that if it was the valve stem oil seals it should really only smoke on start up and on overrun. From what I understand my engine is currently smoking all the time which from what I understand would suggest piston rings - I just can't see it in a "new" bottom end.

#7
Sandy

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I must have misread, I thought you meant it was only smoking at idle, which is typical of stem seals on the TU in my experience, sometimes leading to a stall as soon as you touch the throttle. Blue smoke can only be oil, it would seem odd on a new bottom end.

#8
Grahamrally

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What sort of compression figures were you getting? A leakdown test will show you how much blow past the pistons you are getting which is related to compression, so you should be able to get a good idea how good the rings are through your compression readings. I assume you were getting something like 170+ psi?

Other than that it could be the stem seals if they have been sat dry for a year or so, the rubber on them does degrade quite quickly especially if they were in open air. Really depends if the smoke is constant all the time, or whether it smokes on lift off. Usually if it's constantly smokey and gets a little less when you rev it, it means stem seals. If it's on lift off then it usually indicates knackered rings.

If you are getting good compression and when you add a little oil down the spark plug holes the compression doesn't increase then you can assume the rings are spot on.

Well at least it's running finally!

Edited by Grahamrally, 04 November 2006 - 07:39 PM.


#9
trogboy

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Well at least it's running finally!


Amen to that - I thought I'd never get there!

I should be picking it up on Monday or Tuesday of next week as they are going to be spending a little time with it on the rolling road trying to improve the progression as at the moment there is a big flat spot.

Once I've had it a couple of days I should have a better idea of exactly when it is smoking so I can take it from there.

#10
christopher

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Hmmm :blink: sounds very cagy to me too something is not right here at all.

The idle of carbs is really down to the mixture screws, throttle position and balancing, and dizzy position in my experience. If one or all of these are incorrect it can me impossible to get a decent idle. Its kinda really an art because its very easy to get wrong but gets easier the more you do it.

My standard idle jets were ok to start the car and idle it even with a different cam (although I changed these later since they were a bit lean).

Also a factor here is the carbs. They may be dirty, have a snapped idle screw (only seen when you fully withraw it), broken float and god knows what else. Have you checked these before?

Another issue also to consider is..do you have a standard TU24 cam? Did you measure the cam lift?

Edited by christopher, 06 November 2006 - 03:57 PM.


#11
trogboy

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I have just spoken to this guy again. He is telling me that they are still having problems setting up the carbs and he thinks it is because the chokes are too large! He also described the original jet settings as being "wierd and wonderul".

As I have said before the head/cam/carbs are effectively stock TU24 albeit whilst the bottom end is TU3 so should the jetting change that much or does this guy not know his arse from his elbow?

The smoking now sounds like valve stems/valve stem oil seals. Can the seals be replaced in the car on a TU engine? if so what special tools do I need?

So many questions.

#12
christopher

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I have just spoken to this guy again. He is telling me that they are still having problems setting up the carbs and he thinks it is because the chokes are too large! He also described the original jet settings as being "wierd and wonderul".


sorry but what a load of C%ap. 34 chokes are large for a 1,3 engine yes. But this is no ordinary 1,3 engine.


The smoking now sounds like valve stems/valve stem oil seals. Can the seals be replaced in the car on a TU engine? if so what special tools do I need?


I have never tried on a TU. But you could do it with compressed air in the cylinder or similar methods


Lets see how it goes when you get it back :blink: But I would't let him change the chokes if it was me.

Edited by christopher, 06 November 2006 - 04:22 PM.


#13
bren_1.3

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The smoking now sounds like valve stems/valve stem oil seals. Can the seals be replaced in the car on a TU engine? if so what special tools do I need?


the stem seals arent rubber, they're plastic. im sure you know this. theyre not readily available, i wanted a set of 8 for my build for piece of mind. they had 3 in stock and the rest where a couple of weeks on order!

its a head off job unfortunately. you've to remove the spring and top hat to prize the seal away from its seat and get it out. you need nothing more than a plastic container to keep a hold of the collets, and a valve spring compressor, 15 - 20 quid from halfrauds or similair. valve out job but very simple in terms of procedure to do.

can lend you my compressor *if* it comes to that.

I have just spoken to this guy again. He is telling me that they are still having problems setting up the carbs and he thinks it is because the chokes are too large! He also described the original jet settings as being "wierd and wonderul".


can you provide him with what the original settings are in the carbs?

Forgot to ask: hows it driving, apart from its flat spot and smoking? pleased with the drive and power it gives or not?

Edited by brens_1.9_wide_arch, 06 November 2006 - 04:39 PM.


#14
trogboy

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Hey Brenan, Chris,

I thought about replacing the valve stem oil seals in-situ after I posted earlier and realised I was being a muppet. Wasn't really thinking straight at the time. To get to the seals I'd have to take the springs and rockers off anyway so I'd have to take the head bolts out regardless.

I've got all the kit to do it (again) and you're right about the wait for the parts. It took a week or so when I bought the set that are on the head now, about this time last year.

I don't really have complete confidence in this bloke as he suggested trying a DCOE idle jet holder! Great plan. I just wonder what else he is changing without really understanding the difference between DCOMs and DCOEs. He also tryed telling me that my engine must be really different to the TU24 because he had changed the jetting so much. When I said they shared the same head, cam, carbs, inlet manifold, dizzy and CR he said there must be something else. I pointed out the shape of the piston crowns were different and the size was a bit bigger but he just kept saying that there must be something else! I think I'd probably have noticed by now if there was.

When I pressed him about what made him think that the chokes were too large he tryed to fob me off by saying he'd have to go into the technical detail of how a carb works! I'm not an idiot FFS! I may not have the practical experience but I can understand a lot of the theory.

Sorry - I just have a bit of an issue with anyone who wants me to trust them but won't tell me the reasoning behind what they think the problem is, especially if I'm paying them to do the work.

#15
christopher

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I thought about replacing the valve stem oil seals in-situ after I posted earlier and realised I was being a muppet. Wasn't really thinking straight at the time. To get to the seals I'd have to take the springs and rockers off anyway so I'd have to take the head bolts out regardless.


:ph34r: :D You are of course totally right

#16
bren_1.3

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I don't really have complete confidence in this bloke as he suggested trying a DCOE idle jet holder! Great plan. I just wonder what else he is changing without really understanding the difference between DCOMs and DCOEs. He also tryed telling me that my engine must be really different to the TU24 because he had changed the jetting so much. When I said they shared the same head, cam, carbs, inlet manifold, dizzy and CR he said there must be something else. I pointed out the shape of the piston crowns were different and the size was a bit bigger but he just kept saying that there must be something else! I think I'd probably have noticed by now if there was.


he's just clutching at straws really, i forget what hes actually trying to do? he's trying to get it to idle? or is he getting rid of the flatspot?

When I pressed him about what made him think that the chokes were too large he tryed to fob me off by saying he'd have to go into the technical detail of how a carb works! I'm not an idiot FFS! I may not have the practical experience but I can understand a lot of the theory.



hmmm i think its high time you fobbed him off! hes obviously got no real clue, and again trying anything and everything to do whatever it is he's doing simply hasnt worked! sounds like he's messed around with them in a big way. get him to return the carbs to original settings and leave.

#17
christopher

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he's just clutching at straws really, i forget what hes actually trying to do? he's trying to get it to idle? or is he getting rid of the flatspot?



hmmm i think its high time you fobbed him off! hes obviously got no real clue, and again trying anything and everything to do whatever it is he's doing simply hasnt worked! sounds like he's messed around with them in a big way. get him to return the carbs to original settings and leave.


I think I would be inclined to do the same here trogboy

You probably know this...and he should do

The DCOM has 5 progression holes like the later DCOE's so need a slightly larger idle jet then their usual DCOE counterparts and the main jet assembly has the air corrector jet built into this holder. If he needs to change the air corrector jet then he needs to use stock DCOE holders. Otherwise everything is the same as DCOE.

I still can't get my head around why you couldn't get an idle with the standard jet settings on a 1360. The compression may be a bit different and the engine is a bit bigger but otherwise...no. The cam is wilder but a standard TU24 will idle happily at just below 1000rpm

As I mentioned before the last time I reworked my carbs I tried to set them up myself instead of going to my local carb tuner. When they were not balanced properlythis was just impossible below 2500rpm. After this it was actually ok (and I have a cam with much more lift at TDC).

Incidentialy, my local carb tuner does all the tuning without a rolling road. If one have enough experience then this is how it used to be done in the old days.

The different cam on mine needed just a slight bigger idle jet (DCOE spec) all other setting were left the same.

You you want to have a go yourself to check the carbs, balance, and set idle I can help you. Just give me a shout

#18
trogboy

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Bren - He soon sorted the idling problem by using a larger jet. He is trying to sort the flat spot now. When I spoke to him yesterday he though he'd almost got it. We'll see what he says this afternoon.

I wonder if the problems he is having are because of the oil it's burning. The guy should know what he is doing really as he is an authorised dealer. When I looked round he had quite a few cars running weber side draught carbs in the workshop and seemed to have heaps of spares.

If I give up on him now I am still going to have to find somewhere else to look at it for me and I don't want to have to travel too far.

I don't know, i'm gonna have to think about this.

The carbs were definitely balanced enough to idle when i had it, (visual and with a synchrometer). I am beginning to question myself now and am wondering if I have cocked some thing up with the build.

Sod it

#19
stu_woac

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still sounds like this guy is trying to hard, my tuner got my car up and running in four hours from being nothing at all, one problem he had was my coil was knacked so it wouldnt run properly, wheres the flat spot, is it on change over?? was the floats ok?

#20
trogboy

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Right here's an update,

I got the car back on Wednesday night. I had a long chat with the guy who was doing the work and left feeling much better about what he'd been doing and whether he knows his arse from his elbow!

When I first started her up there was a little smoke but it quickly went away. The rest of the trip home was pretty much in the dark with nothing following so I couldn't check when she was smoking, however when I pulled up at home it was really noticable when idling.

I took the car into work on thursday and friday and noticed that appart from initial start up it doesn't smoke at all until it gets warm - then is smokes like a good'un when pulling away, idling and on gear changes. In ththe car park at work when I had just stopped I let her idle for a couple of mins and she started to smoke a little. Opening the throttle just helped to obscure me from the outside world in a choking cloud of blue smoke.

I figured it was likely valve stem oil seals as everyone seemed to think so (including the guy who had been working on it) so I prepped my self to take off the head and change the seals today.

This morning I took her out for a spin to warm her up for a compression test before I started work. Again a little smoke on startup but then nothing to speak of until she was warm when she started to smoke pretty bad again.

Anyhow compression test results:

110, 110, 110, 115 - Crap!

The first thing I did was to check the cam timing incase the vernier had slipped but it was OK.

After a teaspoon of oil in each bore.

145, 145, 150, 145 - Double crap - could be the rings.

When I had checked the compression when I was trying to set it up myself it was showing 165-170 on all cylinders. I don't get it! The bottom end had 0 miles on the clock before the build and now it only has approximately 150.

The last time I tried to use the head and carbs I was forced to admit defeat because of massive clouds of blue smoke when that got warm. I decided to send the head off to QEP for a visual inspection and a check of the tolerances and it was passed no problem so I put the problem down to the block as it was an unknown quantity at the time.

What is going on? Do you think a leak down test would help?