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Richot1989

Smoking on start-up

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My '89 3.2 recently had a top end overhaul (at 55k). Valves, guides, rings etc., were replaced.  I've done 300+ careful miles since (advised not to exceed 5krpm for the first 500 miles).

However, if the car hasn't been used for several days, it gives quite a puff of smoke on startup.  

Should I expect this after a top-end rebuild?  

Your expert thoughts please.

 

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How have you been running it in? Plenty of downhill/deceleration off the throttle running?

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Should be fine if its only for a few seconds on startup?

Hot oil levels ok?

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Hi Guys,

Thanks for your prompt replies.

As recommended, I haven't exceeded 4k rpm yet and I have driven it gently, mainly on the flat - no steep inclines - up or down. 

Oil level (hot & on tickover) is correct.

Perhaps it will settle down with more mileage (and spirited driving!) allowing everything to bed in.

It only smokes on start up if the car has been left for several days - occasionally not at all but most times, its quite a cloud ( invoking quite a negative comment from her in doors!).

I haven't noticed it smoking on acceleration or deceleration,  and it doesn't smoke on tickover.

I just am disappointed seeing this cloud of smoke have spent a few pennies having the work done.

Are there any restrictors which reduce oil drainage back into the engine when its switched off?

 

Thanks

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4 minutes ago, Richot1989 said:

Are there any restrictors which reduce oil drainage back into the engine when its switched off?

No, just the tightness of the oil pump gears.

Not wanting to start a "which oil is best war", this normal quirk can be make much worse with thin modern oils.

Mark

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Mine did this after my rebuild earlier this year. It turned out to be a leaking exhaust valve seal which had broken. Not only did I have smoke but also an oil leak out of the exhaust flange at that cylinder. Might be worth taking the exhaust off to see if there are any leaks?

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1 hour ago, Richot1989 said:

I have driven it gently, mainly on the flat - no steep inclines - up or down. 

Then you need to do so :smash:

Perhaps it will settle down with more mileage (and spirited driving!) allowing everything to bed in.

Let's hope so, though it's probably already bedded in :rolleyes:

 

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Just an observation, it’s had a top end rebuild and new rings??
Rings are cast iron and the bores are hard plated alloy. 
What are you running in? 
Use your 5k limit, make it work - you should only be seating the rings in the cylinders. 

Just one more comment, they didn’t smoke when everything was new. Why would it smoke after a top end overhaul?

As always, the above is just my opinion.

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Again, Thanks guys.

Yes, spirited driving from now on then (just like before the top-end rebuild) and will also  check out for possible 'exhaust valve' leakage!

 

SWT, not sure which oil they put in - will ask the question. (and NO, I'm not going to ask which grade/brand is best!!!!!!!)

 

Thanks again👍

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A few years ago when buying my wife's Boxster at Porsche Solihull we happened to still be finalising the paperwork right at the end of the day when they were moving cars from the front forecourt. You'd be quite surprised how much smoke on start up was visible!

You've got to bed those rings in. Just drive it normally.

The important thing is to not labour the engine.

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A mate of mine was picking up his brand new GT3 from the main dealer a few years ago. When it was started in the show room, it belched out so much smoke, we all went outside. The car was fine and never gave my mate any engine problems. It did however have gear box problems and had to go back to the dealer within the first week. It turned out to need adjustment of some kind. He got it back a few days later and everything was fine.

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I had a full engine rebuild a few years ago. It puffed a bit of smoke on start up after the rebuild if left for a few days, it did this until I put a few thousand miles on it. I think I did baby the engine for longer than I should have, from memory Running in was kept below 4.5k revs for 1000 miles and driving it very gently. It was still giving a puff of smoke after 1000 miles. After a service that included valve adjustments etc, I started using the Rev range a bit more but not hard use. I guess I was scared after spending so much on the engine rebuild !

Now after almost 6k miles it doesn’t smoke on start up even if left for weeks/months. The last few years I have driven it much harder.....this has appeared to do the engine good. 

Sounds like you need to a few more miles.....

Phil 


 



 

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Hi Guys,

 

Many thanks for all your comments, experience and advice.

Just need to put a lot of miles on it (looking forward to that!!) and see how it improves.

Cheers,

  Richard

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I think the comment about deceleration and in gear down hill is specifically to bed in the rings. Its what I was advised to do when running in my 924 engine after rebuild.

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Ok LesW, living in the Chilterns, we have quite a few steep hils around so will give the recommendation a good try.

 

Thanks again,

 

  Richard

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Hi Guys, a quick update:

The significant smoking on start up continued (when left for a week or so), so I decided to fit a 'oil inlet control valve', made by Rothsport (and supplied by Matt, thank you Matt).

As a result, the start up smoking has been significantly reduced to just the occasional puff.

Positives:

* Greatly reduced smoking on start up after a reasonable lay-up. (wife pleased, enviroment pleased and less coke on the valves etc.,)

* Oil level guage gives  immediate reading  when the ignition is turned on and engine not started.

* Easy to fit (just need cutting a small section out of the return oil feed rubber pipe from tamk to crankcase - opportunity to fit a new one!).

 

Negatives:

* Not cheap for such a small item.

* need to drain the oil tank ( but an opportunity for an oil changel?)

 

Hope this is of interest to some of you.

Richard

 

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Posted (edited)

OMG you're not kidding about the price 😳

(But glad you've found something to reduce your issue)

Edited by Chris_911

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Didn't think that valve would be needed on a freshly rebuilt engine?

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HOW MUCH!

feck me not much more and it's a full day at Centre of Gravity or a sesh at Chip Wizards!

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A day with Wayne maybe but CG will cost a tad more :twocents:

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Shall I start a group buy?:whistling:

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Wonder if it would be a good addition to my 89 engine as it could do with fresh valve guides but reluctant to commission a top end as engine is in good state with leakdowns below 4% and only a small. This is far cheaper than a top end.oil leak.

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Probably would come out the same if you added P tax at checkout 🙄

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2 hours ago, Mondrian said:

Wonder if it would be a good addition to my 89 engine as it could do with fresh valve guides but reluctant to commission a top end as engine is in good state with leakdowns below 4% and only a small. This is far cheaper than a top end.oil leak.

Better to add to your future rebuild fund.

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