Intermittent exhaust smoke on start up
#1
Posted 08 May 2006 - 01:01 PM
#2
Posted 08 May 2006 - 01:08 PM
i think smoke on start up is generally down to worn valve stem seals.
#3
Posted 08 May 2006 - 02:51 PM
#4
Posted 08 May 2006 - 04:22 PM
If you have a high-mileage engine, it may be the guides themselves which are bad. If you have a car with lots of miles on it, consider pulling the head and having it reconditioned.
It is possible to replace the valve guide seals on the car without pulling the head. If you don't have a high mileage car, consider getting a new set of seals and installing them. To do the job you'll need a set of seals, a length of clean rope, and a hook-type valve spring compressor that levers against the rocker shaft. It's about an hour's job.
#6
Posted 08 May 2006 - 06:59 PM
I third the valve guide (seal) comments.
If you have a high-mileage engine, it may be the guides themselves which are bad. If you have a car with lots of miles on it, consider pulling the head and having it reconditioned.
It is possible to replace the valve guide seals on the car without pulling the head. If you don't have a high mileage car, consider getting a new set of seals and installing them. To do the job you'll need a set of seals, a length of clean rope, and a hook-type valve spring compressor that levers against the rocker shaft. It's about an hour's job.
Unfortunately my mini is a high-mileage car. Can replacing the guides be done by a D.I.Y person or is it best to buy a recondition cyclinder head?
#7
Posted 09 May 2006 - 10:12 AM
Never thought of doing it like that !
You can get a reconditioned head for about £150 I think, or try your local engineering people (or Richspeed:). Good time to get the unleaded conversion done if you havent already.
Its fairly easy to get the head off and put it back on again, just take lots of pics of where everything goes, particularly on the carb if you take anything off of that ! When you put it back on make sure that all the studs are seated properly in the block, as I learnt if they arent you end up chewing the thread out of the block and having to get it helicoiled !
Jimmy
#8
Posted 09 May 2006 - 12:48 PM
Jimmyarm, regarding the piston position to keep the valves in place, that's what the clean rope is for. You pull the spark plug and feed about a foot or two of clean cotton rope into the bore/chamber. You pull the engine over by hand using the fan belt until the piston pinches the rope against the head and the valves. This gives you a firm surface to push against as you use the tool to compress the valves. Some will tell you to use a spark plug adapter and compressed air to hold the valves up. Rubbish. I tried it. The valve keepers and spring retaining washer are usually stuck too firmly for that to work.
The valve guides cannot be done on the car and are not in the realm of a DIY job. This is strictly machine shop work. The guides need to be pressed in to the right depth, reamed to size, followed by having the valve seats re-cut to be concentric with the bore of the guides. The valves then should be reground and lapped to the recut seats. If you improvise you'll likely end up with leaky valves. Using a machine shop is money well spent. You'll be surprised how much better your engine will run with the valve train in good order.
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