Adam-M

Hi there,

I've owned my dohc 8v Sierra for a while and it was never an overly smokey car. Now I haven't properly drove the car in 4-5months but I just let it sit and idle in the drive. I was working away from home a little while back and I hadn't started the car for about 1 month and when I did it was very knocky like a ticking sound that lasted about half an hour before it cleared. This has happened before and it went away fine. I always check the oil before starting and disconnect the coil to turn it over several times.

Now the ticking has went the car smokes a lot even when you just start it and let it run for 30 minutes it still smokes when revving. I took it out for some sideways last weekend and left a large plume of smoke.

So either valve guides or piston rings what do you think?

Marc sierra

iTrader: (1)

What colour is the smoke? Blue is oil, white is coolant, black is fuel. The DOHC has a reputation of blowing head gaskets. I would expect that earlier than piston rings or valve guides. Or it is black smoke and it is now running way too rich.

gcfcos

These used to suffer with headgaskets and core plug problems for a pass time. Scrap the engine and get another one, still a few about

Adam-M

I'd say it was more of a blue smoke, my coolant is still nice and clean looking and I'm not getting any sludge in my rocker cover. Suppose I'll just need to whip the head off and see, I've got a spare engine bit dont know its condition plus I've not long just fitted a new timing chain and everything else to this engine

Marc sierra

iTrader: (1)

Mixing the water and oil is not that likely as there is probably only one oil channel from the block to the head, so the head gasket would need to go at that location for it to mix. Better look at the coolant level and check if the systeem pressurizes more than normal.

mk22door

Use the later multi layer steel head gasket if you do take the head off.

finis 1101405

Adam-M

Brilliant mate thanks for that I did think the Ł8 eBay gaskets would be shit lol

mk22door

Like this one, it's the 16v version..



:th:

mk22door

The fibre gaskets have obviously less tolerances to the head warping.

Do your fans come on?, you know when you left it stood ticking over - the twin cam fans are also notorious for not coming on when they shoud

Adam-M

My fans are on a switch mate I always switch it on, car never actually gets that warm and doesn't pressurise the system either very strange isn't it.

gcfcos

U say the top end taps or knocks for half hour from cold? Maybe best to just put your spare head on it but change the stem seals on it while
Your doing it. At least that way with the head off u can check for bore wear and scoring etc

mk22door

My bet is the valve stem seals have probably dried up and oil is getting into the combustion chamber causing the blue smoke, usually worse when the car has been sat overnight then you start it up and get a nasty load of smoke.

A lot of people dislike these engines, from what I've read it's down to Ford using a bad choice of headgasket that was getting eaten by the coolant that they used/recommended, theyrectified this with the later gasket and different coolant on the 16v DOHC Escorts & Scorpio's - plus the chain timing issues- not always popular...

mk22door

Ha gcfcos beat me to it whilst I was typing!

Adam-M

I think your right mate, I'll whip the head off and take it to work and skim it lightly, fit the mls gasket with new head bolts and seals. If anything else needs replaced I'll rob it off my spare engine.

Engine is very quiet now the ticking noise went and left the engine smokey, I know what people say about these engines but mines took me to the ring and back including a few hard laps without a single problem, 1700 mile round trip.

Marc sierra

iTrader: (1)

That's actually not really true. The reason for them not to come on is that ford fitted a switch that makes the first one come on at 100 degrees and the second fan at 110 degrees. Replace the switch with a red one from a Escort/Mondeo diesel and the first fan comes on at 95 and the second at 100 degrees.

Adam-M

Just checked again it's defo blue smoke and smells like oil just hope it's stem seals and not rings

gcfcos

Not good :-( hope u get it sorted buddy

mk22door

Which is basically what I said without going into the details

Marc sierra

iTrader: (1)

The way you stated it sounded to me like the fans themselves are unreliable, so I only wanted to explain what the real problem is.

dojj

iTrader: (3)

If the fans aren't used they tend to seize up and then they blow the fuse and no fans at all
The reason they kick in so high is that the engine is more efficient at that temp
Change the fan switch while you have the front end off
You should also invest in a new chain kit along with the tensioners if you want peace of mind in the long term
Remember to use thread lock on the chain guide bolts as they had a habit of coming loose
But other than that you need to pull the tappets and pump the oil out as that's the source of your tapping
The oik will be the stem seals as mentioned before
Skim the head only if it needs it

Adam-M

The chaiN has done about 2k mate I fitted it with all new guides last year, strange but the smoke seems to have cleared and I've done absolutely nothing apart from run it ?

dojj

iTrader: (3)

If you leave it standing they might have simply leaked part the seals, if it's not the residual oil burning off and carries on then think about it but the cost of doing them probably outweighs the effort of topping the oil up lol

Adam-M

Haha I like your thinking mate, I'll see how she goes after I mot it and put it back on the road.