Thread: Smoke at start up

Originally Posted by JDNSW

If it is blue smoke it is almost certainly valve stem seals.

John

^^^That

Easy repair, just need a fitting to fit the plug hole and add compressed air, then a tool to compress the valve springs, swap the seal and all is well

Originally Posted by rovercare

^^^That

Easy repair, just need a fitting to fit the plug hole and add compressed air, then a tool to compress the valve springs, swap the seal and all is well

Correct if it is the cup seals. It also helps if when working on the cylinder in question, the piston is at top dead centre. If the vehicle is diesel, the compressed air is not needed. If it is the O-ring seals, the head must come off.

Aaron.

I think I have the same problem. I have a new set of valve stem seals waiting for me in Katherine when I get around to it. I seem to recall that they're the same as Ferguson tractor ones.

My smoking, though, only occurs when starting the engine hot. I find it takes quite a bit of cranking to get it started, and then it sends out a short thick belch of smoke. I did find a way around it, but it's completely impractical for everyday use - lift the air cleaner hose off the carby before starting. It seems to percolate fuel in the carby when hot and not running, and the Zenith doesn't have an atmosphere vent like the Holden Stromberg. I'm thinking it saturates the air in the hose with fuel vapour and this makes it hard to start hot. Starting from cold is just fine.

My engine is also about 18 months old, but has always done it. It's on its second set of valve stem seals, the first set shattered like glass when I tried to get them off. Hopefully, the set of MF seals my mate has for me will be heat resistant. I have found out that PBRs black plastic seals (eg. wheel bearing, transmission, timing case) are not heat resistant. Maybe some of these valve stem seals are made cheaply as well.

Dan.
69 2A 88" pet4, 74 3 109" pet4, 68 2B FC pet6.

Originally Posted by Aaron IIA

I will address each numbered point.

1. How many miles has the engine done since the rebuild? Were the valve stem seals replaced? Were the valves replaced? Were the valve guides replaced?
She has done under 8500 miles and in that - only a couple of longer trips as I drive her these days to / from work. Although I haven't looked, I did pay to have all these thing replaced and (fingers crossed) that is what happened.

2. When I rebuilt my 2.25L, I could see daylight between the valve stem seals and the valve stems. The engine was not consuming more oil than normal. The valves were a good fit in the valve guides.
This engine doesn't consume any more oil than normal (although it could do with a change soon). When the head was done - the report back was a positive one.

3. The oil pipe at the back of the head is actually the pressurised oil feed to the head. The oil drains from the head throught the channels for the pushrods.
Thanks mate - this stops that line of thought that I had.

I would not be worried about a puff of smoke at start up. If it puffs every time after idling for a while, such as when taking off from the traffic lights, it may get a bit annoying and warrant investigation. If your engine has the later style valve stem seals, the version that are like little cups that slip over the valve guides, they can be changed without removing the head. If your engine has the early style valve stem seals, the O-ring version that sits inside the valve guides, you need to remove the valve, and hence the head to change the seals.

Aaron.

Thanks Aaron for the help. My smoke is only at start up and only a small puff out the back. Nothing a traffic lights etc. I reckon that I shall investigate some new seals to instal over the christmas break.

Thanks all again.

Dan - when you get a chance can you pm me the detail re these seals you speak of and i shall investigate them from this end as well

Originally Posted by dandlandyman

........
My smoking, though, only occurs when starting the engine hot. I find it takes quite a bit of cranking to get it started, and then it sends out a short thick belch of smoke. I did find a way around it, but it's completely impractical for everyday use - lift the air cleaner hose off the carby before starting. It seems to percolate fuel in the carby when hot and not running, and the Zenith doesn't have an atmosphere vent like the Holden Stromberg. I'm thinking it saturates the air in the hose with fuel vapour and this makes it hard to start hot. Starting from cold is just fine.
..........

I think your problem with starting is probably excessively rich mixture for a hot start, and removing the hose gives a slightly weaker mixture. The rich mixture could have the mechanism you suggest, but I think it unlikely. Another possibility is a partly blocked aircleaner, or incorrect float level, but again, I think these are unlikely. The most likely cause is that the top cover of the Zenith is warped, preventing a good seal on the gasket and O-ring, or the O-ring is not good. I have also had burrs on the screws holding the emulsion block to the top cover prevent the top cover from seating properly.

John

Here we go again folks .... And reading what I have previously said I realise that I have been very lazy when it comes to addressing this issue with olmate

I replaced my valve seals over the weekend, the head is good and clean now and all has been cleaned up. Well - as the motor was rebuilt just over 2 yrs ago, it should still look like new inside it I reckon.

All adjusted fine and she goes very well up the road BUT still puffs smoke at start-up in the afternoon Who reckons I am frustrated now

So what's next - she starts well in the am, goes like a treat to work and then (when I start her in the arvo to come home) I get a puff of blue smoke before she idles nicely. What to do?? There is no smoke whilst driving or at lights etc its just at the one time in the aro when I start her up

Any thoughts out there ?

Is it a bit cranky when hot or warm? Fuel smoke?

I've given up worrying about it with mine.
They are worse when warm. Seems like fuel smoke. Maybe a trait with Zenith carbys with that notorious warpage on top plate when warm.
Mine has the O ring fitted as well.

Tony