It has been some time since I last posted on here...we have recently dusted off our fiat after a year or so in the garage, with just the odd run when weather allowed. Great to be back on the road in earnest, but not without the odd problem... noise from front wheels/ sooty plugs aside, biggest concern is a sneezing engine...

Under high revs, when I let off (both in gear and not) it is not unusual for an occasional sneeze from the engine bay, which results in a coating of oil over the tinware on the thermostat side of the bay. It is more likely to happen when the engine has warmed up, but can occasionally occur in the first few miles of a drive.

I have recently replaced the head with a refurbed unit that came with the car, and the sneezing persists. It seems as though oil is coming through the rear most hollow bolt - but I'm not 100pc certain of its or origination.

Compression is fine, but does that completely rule out rings? Current oil is Halfords classic and I may try 10w60 (better for high temp engines?) - changing oil would also allow me to check for ring debris in the sump - but otherwise I'm at a loss. I would be very grateful for any pointers/ diagnosis suggestions, before I reluctantly open up the bottom of the engine.

I have a 650 engine, with alloy sump and rocker cover, fzd carb and 123 ignition. Oil level is half way between min/max. Spark plugs are new and NGK BPR7HIX - previous plugs (BPR7HS) were black with soot. Have since leaned out mixture and will keep an eye on new plugs - my thoughts are that the sooty plugs is unrelated to the sneezing..

If oil is actually coming from the hollow bolts that can only be a leaking head gasket. But thermostat side leak points to one or more pushrod tube seals. It's worth removing the thermostat housing to check. Do you ever retorque the head?

The sneezing sound is most likely carb related. I had a similar issue when I had a 126 carb on my 500cc engine. Only sneezed when cold though. The oil mist might also be from the dipstick. I had a similar issue where oil was getting squirted out the center hole of the dipstick. A little epoxy cleared that up for me.

Thank you for your replies. I also thought it could be the carb, but the oil appearing after any sneeze and which is more substantial than a mist led me to believe otherwise.

The head gasket is relatively new and head is torqued down, which suggests perhaps not the hollow bolt. However, the heat shield on the inside of the bonnet had oil on it after the last sneeze - if the oil came out at force it would then splatter the rest of the engine. I suspect a bit more investigatory work is needed to confirm source of oil, but difficult when it occurs when the engine is under heavy load. My other suspect would be the rocker cover, but the gasket seems ok.

I have this issue too. New reconditioned heads, new vlaves, new head gasket and I just re-torqued a couple of months ago, new tubes and seals. I get oil on that side of the engine bay as well. Mostly on the heat shield over the muffler. Not a lot, but enough to annoy me. I can't figure out where it's coming from either. It it's tube seal related then I don't think there is anything we can do as I doubt we want to tear down the engine again! :bang:

oil can come from anywhere in my experience, because of the fan and generally windy engine bay it can be blown anywhere and everywhere.
check the cam cover and gasket first, it took me a few goes to get this oil tight, only shows up at high rpm and engine hot - check the cam cover is flat as well! The leak was on the front edge of the gasket, I smeared it with some blue hylomar in the end, the gasket tended to be extruded in or out as I tightened the bolts down
popping or 'sneezing' on the overrun after high rpm can be indicative of a carb or timing issue, mine also did this which I managed to cure by setting the timing with a nice snap on gun at 3000 rpm, rather than the static timing.
I still get a bit of a dark misting appearing on the rh grilles of the engine cover after a long run and not washing it, so I suspect there is some oil being vaporised and chucked out of the thermostat flap. Keeps the rust at bay I suppose...

Labman - it is comforting to hear I'm not alone, although sorry to hear of your woes!

For me, I don't think it is the pushrod tube seals as I recently replaced these when I took the head off - unless new seals take time to bed in to become effective?

As a first step to further diagnosing, I plan to change the oil over and will have a keen eye on any bits of metal that come out of the sump. Will post my findings later this evening...

Greetings Gents, Oil leaks a real pain in the A**e You can guarantee that if you have oil running down the front of the engine it will be the rocker cover, this can also blow onto the dizzy heat shield but only at the front. If you have oil blowing onto the shield from the right side again it will be the pushrod tubes. It just seems that no matter how careful you are getting them dry they will start to weep eventually. Unless you have smothered the top of the tubes with a good sealant that will withstand heat changes it happens. My car has remained dry for 6 months of driving and now the drip tray shows evidence of oil loss from the right side (viewed from the rear) of the crankcase, a close look with a small mirror shows that the top seals of the rear two tubes are weeping You can either replace them or clean up when you get home

Ian.

There is a fix for pushrod tubes. Buy the Volkswagen beetle upgraded axjustable tubes - about £7 ea

Quick update: nothing in sump other than oil. I went ahead and changed it to 10w60 anyway.

I took a closer look at the new rocker cover gasket and I'm not convinced it fits the head/tinware at all well - it overlaps the edges on the rocker cover, reducing the width of the gasket that sits between the head/cover. I reverted to an old gasket and blue hylomar, which held in place on start up - an improvement over the first time I fit the new gasket. I will order a new gasket, but keen to know of which is better for cast rocker covers - rubber vs cork?

Interesting to hear of the fix for leaking pushrod tubes - I think these are the VW ones that will fit -
http://www.megabug.co.uk/empi-sprin...of-8-1600cc-vw-ac--t25-19-21-81-91-5885-p.asp is that correct?

Finally, timing as a cause of sneezing... I have a 123 ignition and have always assumed timing is set and forget, even if set static. Is this not the case? I will try to get hold of a timing light with rev counter to check though. 650cc so 18deg BTDC (and so 25mm clockwise from TDC mark), is that correct?

Plenty more questions I'm afraid, but does feel as though I am making progress (mostly in my understanding of the engine - hopefully progress of leaks and sneezing will follow shortly!)

The spring-loaded push-rod tubes that you can buy from a number of sources have the big advantage that they can be fitted with the cylinder-head in-situ---so much easier than trying to twiddle 5 tubes into correct alignment as you lower the head into place. I used the thicker of the tube seals, and the springs are strong enough to compress the seals quite well.
I personally would use the 'ruberoid' rocker-cover seal (as I would also recommend the 'ruberoid gasket for the sump)--fit carefully on the head, and inside the cowling, with a light smear of blue Hylomar.

Do the pushrod tubes come with a thicker seal? I've only know the standard fiat seals. Otherwise all clear, thank you!

Thats the tubes I've fitted. I have three spare - and i believe they will sell them singularly. So if anyone wants them..

Andrew - certainly interested - I'll drop you a pm

A quick update and thanks:

On the gasket, the rubberoid gasket together with blue hylomar is holding well, with no additional oil in the bay (although I still get the odd drip from the previous coating the bay got)

On the sneezing, I advanced the 123 ignition by turning it slightly (rather than changing the setting screw). This seem also seems to be holding, with no sneezing as I let off at high revs. I have picked up a induction tachometer from ebay (£6), which I plan to use with a timing strobe to confirm the advance at 3,000rpm - but at least, so far so good

I also noticed that whilst reinstalling a new rocker gasket, that the choke on the FZD was not fully returning, which may explain the sooty plugs... I'll get them out again after a long drive, and see if they have cleared up. But for now, all is well.... save a "fut fut fut" noise from the front right wheel. No doubt more on that to come.

Thank you to all those who contributed! :worship:

If you are having a problem with the choke on an FZD then you could just remove it as many cars run without it. The pump device seems to be the equivalent of the fuel enrichment / choke on the standard Weber carbs.

I trust those in the UK have enjoyed the unusually good long weekend weather... I am just back from a three day 500 road trip to North Devon - a little over 200 miles all in. The outward leg was near flawless. However, coming back today the sneezing and oily bay issue returned.

It started running rough after an house and having stopping for petrol, it struggled to restart but did fire up after a few minutes. Then it worsened at the bottom of Cheddar Gorge, so we pulled in. It was sneezing when I pushed the clutch on high load, and also sneezed when in gear going downhill (with no throttle). I opened the lid and saw fuel dropping from the carb manifold - one of the nuts holding the fzd to the manifold has loosened, despite being a relatively new nyloc. I then noticed the ramflo filter was loose - again, the two small nyloc nuts inside the filter had loosen!!

I tightened the nuts and then left it for 45 mins to let it cool. It then started up ok, but continued to run rough and steadily got worse. I had to use the hand accelerator to keep revs up, but it really struggled at times. We did make it home, but was a nervous last hour or so.

I took a few photos...seems as though it could be the breather bolt, but could just as feasibly be oil splashing off the bay lid and covering the bolt.

I would be very grateful for any thoughts/ advice.

These issues aside, it was a brilliant weekend in the 500! Our ten month old seemed to enjoy herself too and was very happy in the back with the roof down!