smoking 300tdi

[cotleigh crasher]

Hi Folks

I know that other topics have covered this one but none of them quite match my problem, so I thought I'd start a new topic and see what comes in.

I've had my 300tdi 110 for about a year now, ever since I've had it, it has belched out blue smoke when started from cold. This clears after about 200 yards and doesn't reoccur when re-starting unless it stands for four hours or more.

Some time ago I changed the glowplugs and found that no. 2 had fresh oil (not diesel) on the tip. I figured that the valve stem seals were leaking oil into the cylinder when standing overnight.

3 weeks ago I renewed the stem seals and problem solved, just a puff of black smoke when starting.

A couple of days ago it suddenly started smoking again, just like before, so last night I changed the stem seals again, thinking I may have damaged one when fitting it.

I didn't find any problems with the seals as I changed them and when I started it earlier it still smoked and again, it cleared after 200 yards or so. It seems to smoke more if I back off then apply the throttle.

I've disconnected the oil breather from the air intake and connected it to a catch tank, so its not that.

It hardly uses any oil at all, only needing a top up of half a litre every 2000 miles or so and the engine seems to perform ok, no misfiring or loss of power.

Any ideas anyone?

Incidentally, I read on other threads people asking if the seals can be changed without removing the head. They can and its really easy using the tool I designed. Just remove the rocker shaft, bring the appropriate piston up to TDC and attach the tool to either a rocker shaft stud or a piece of studding screwed into a bolt hole, with the 'heel' of the tool on the edge of the rocker box between the injectors (pad it with a piece of thin plywood or similar) wind down the nut and bingo!

I've tried to attach a plan of the tool but I'm told that I can't upload this type of file (word document) if somebody can tell me how to do it I'll gladly share the plan.

Ralph

[Tanuki]

If the smoking problem is cleared by replacing the stem-seals, but returns shortly afterwards - this rather indicates that the *valve-guides* are worn and the valves are slopping/rocking in the guides, which will knock-out new stem-seals in a short time.

What mileage has it done?

After 150,000 miles it could well be due a top-end overhaul [new valves and valve-guides all round, along with new seals].

--Tanuki

"No man is totally useless: he can always serve as a horrible reminder to others".

[cotleigh crasher]

I did think that, and to be fair there is about 0.5-1.0mm of lateral play at the top of the valve stem. But surely it would smoke all the time, especially on the overrun, not just when its cold?

I have no idea how many miles the engine has done as its a replacement 300tdi in a '91 110.

To be honest, I'm a bit afraid to take the head off in case I find other horrors inside? (chicken?........oh yes!)

[cotleigh crasher]

Finally worked out how to attach the file (hopefully!)

As I explained previously, just remove the rocker shaft, bring the appropriate piston up to TDC to support the valve, fit the tool over the rocker shaft stud or studding screwed into bolt hole with the 'heel' resting on the edge of the rocker box between the injectors (suitably padded), fit the nut and screw down to depress the valve spring....easy!

300tdi valve tool.pdf

I hope it will be of use to those of you who, like me, can't be arsed to remove the head to change stem seals.

With this tool the whole job, including removing the bonnet etc, can be done in about 3 hours, maybe less if you drink less tea.

[cackshifter]

Sometimes as the boost seeps up the valve guides the seals blow off, and sit further up the valve stem - might be worth a quick look to make sure none of yours has done that. If so, and replacing doesn't work, it suggests it's time for new guides

[cotleigh crasher]

As I said, I changed the seals the other night for the second time and found nothing wrong with them.

Having given it some thought, I reckon whats happening is that when a valve is left open overnight its being pushed over by the rocker, due to the small amount of play in the guides, this is distorting the seal and allowing oil to run down the guide and into the cylinder to pool in the combustion chamber in the piston crown.

During normal running the valve isn't open (and seal distorted) long enough for it to allow a significant amount of oil into the cylinder, therefore, no smoke on normal running, only when first started from cold. I'm assuming that a small amount of oil = a lot of smoke.

It looks like its going to be a head off job after all.

I might just look around for another head at a reasonable price, do a full service on it, swap it over then sell mine afterwards.

Sounds like a plan to me!

Thanks for the advice chaps, as always you've come up trumps.

Anyone got a good head for sale?

Ralph

[Tanuki]

If there's any lateral 'slop' in the guides (which you've mentioned in a previous post) then this is likely to mean your newly-replaced valve-stem seals will be pushed about in unhealthy ways. When you park up and the engine cools the seals will take a "set" depending on where the valve-stems happen to be.

Oil then leaks down the guides.

When you start the engine again you get an initial belch of blue/white smoke, followed by a decreasing smoke-trail as the seals gradually warm and become more-flexible so letting them mould back to the profile of the wobbling valves.

My approach would be to pull the head and send it to a good engineering-shop. They'll measure the wear in the guides - and from what you've already described, class the wear as 'out-of-spec'.

Given that the head's already off I'd be going for an entirely-new set of valves, and Phosphor-Bronze guides.

[Troll Hunter]

Tanuki,

From your suggestion above, I assume that the normal tappet guides, as supplied by Paddocks, are not phosphor-bronze. Who supplies these higher spec ones, please?

Also, if I replace my valves and guides, should I also replace the valve seat inserts, and is this a job I can do myself, or would I need to go to an engineering shop. I have a fair selection of hand and power tools, but no press.

Is there anything else I should consider replacing while I have the head off?

Many thanks,

Mike

[Ash.Witty]

removing the valve seats isnt too hard of a job, if you are fitting new valves to you can use the old ones to remove them.

Grind down the head of the valve so it sits inside the valve seat, then run a ring of weld around the valve seat and valve head to weld them together, then using a copper hammer tap the valve stem from the other side and this will push the seat out.

then change your valve guides.

press new seats in, best using liquid nitrogen or leave them in the freezer overnight with it turned up to the max, this will allow a little shrinkage and will be easier to fit.

then you can cut the valve seats to the required angles and lap the new valves in.

Hope this helps

Ash

[cotleigh crasher]

The saga continues.........

When I got home last night I noticed 'vapours' coming out from under the bonnet.

Closer inspection revealed that they were coming from the temporary catch tank (plastic bottle) for the breather pipe from the cyclone breather thingy. There was also an inch of water in the catch tank.

I checked the coolant and it took about 2 pints to top up. It was last checked about 3 weeks ago and was ok then.

When I took the oil filler cap off with the engine running, the vapours then came out of there, not the breather pipe. I wouldn't say that they were belching out, but they were certainly being propelled, not just drifting out.

The vapours don't smell of oil or diesel but smell a bit like when you spit on hot metal, so I'm guessing its steam being emitted.

There's no yoghurt in the rocker box yet, but there seems to be a tiny amount starting to form on the underside of the oil filler cap, you could cover it with your little finger.

So, the question is, is it the head gasket or a cracked head? or both? or neither?

Also, is it safe to drive like that or is it an early warning that something is about to go bang?

Any ideas anyone?

[Tanuki]

Water in a "catch tank" is not necessarily a sign of issues: the vapours exhaled from a crankcase breather do contain a significant quantity of water which is produced by normal combustion-processes. It's the same water that causes "steam" from the exhaust on a cold day - just that in your case it sounds like you've got a bit more than usual of the combustion-gases getting out of the combustion-chamber and into the crankcase.

Worn piston-rings can cause this, so can worn exhaust-valve guides. Of course a cracked head or failing head-gasket can too!

My approach would be to get the head off.

Have it crack-tested. If it passes, have the valve-guides replaced and new valve-seats fitted. Also get the head checked-for-flatness then maybe also a "facing" skim (5 thousandths of an inch) to make sure the surface is perfectly smooth.

While he head's off you can check the bores for any signs of scoring and whether the pistons are showing signs of wear (the pistons should not wobble about when you try to press them from side to side!).

If the bottom end looks good, reassemble it all with a new head-gasket.

--Tanuki.

[ejparrott]

Don't worry too much about a little bit of mayonnaise on the filler cap, its not a confirmed indicator of head failure on its own. Mother-in-laws car has it constantly, and its because she drives 2 miles to work, 2 miles home, 2 to work, 2 to home. I give it a going over now and again and clean it all out, but after a few weeks its back, and yet it doesn't loose any water. The last time I did it the wife promptly thrashed it from Dudley to Rugby and back, and it was still clean two days later!

[cotleigh crasher]

As I mentioned in my last post, it has lost a fair amount of water, so that's obviously gone somewhere, not just evaporated.

I've now located a Turner Engineering cylinder head, complete with valves etc on a well known auction site, with only 500 miles on it, all for just a few quid more than testing and re-building mine would cost, so next weekend I'll do the swap over and de-coke it at the same time.

It'll be a good opportunity to check out the bores and pistons, hopefully they'll be ok as I'm fast running out of funds.

Thanks for all the advice guys.

I'll let you know how it goes...........