Irrespective of looks, that STRONGLY suggests a bad gasket face, and/or a cracked head.
Here is a gasket I have. Made in England but extremely thin?
Could this type be designed for going either side of a compression plate?
I don’t think it specifically was made for [ or not] de-compression plates.
It was the type use irrespectively. Presumably the plates weren’t needed in countries with higher [ relatively] octane fuel
I don’t know whether all the cars that came to Aust had them, I do have a decomp plate kicking around somewhere , presumably from a local delivery car.
There are a few of tem around. It’s only one slight step up from one I sa w that was also painted to look like marble [ part of a fleet of Mk Vs so finished.
Unfortunately from a slight distance it just looked dirty.
There is even a stretch 1 1/2 litre Mk IV.
Yes, the decompression plate is pretty much unknown in the US and I’ve never seen one. The gasket I used was .009" thick in the uncorrugated areas.
Well. I have had the head inspected and no cracks. In fact it is in good condition.
The issue of the leak between cylinders came down to the head gasket.
What was found was if the head gasket was installed correctly (generally with the fold around the cylinder bores facing down) the gasket then didn’t line up with the chambers of the head and half entered the chambers although looked fine positioned on the block. If you turned the gasket over it lined up better on the head but was basically upside down.
On comparison to a new head gasket, and other NOS ones I have, there is no difference in the positions of the bore holes if either up or down facing so there was something amiss with that previous head gasket.
I have the head back on the car but came down with a dreaded flu before I could finish.
I was however informed by the local early SS / Jaguar club of a possible point for smoking, which is also an issue I had.
The inner head studs actually pass through the inlet manifold. If these head washers and nuts dont seal against the stud it can allow oil from the rockers being drawn into the inlet manifold.
While I was assembling the head I took the following photos of a stud and my remedy yet to be proven. Hopefully with the washer and nut fitted that should seal this area.
Regards, Graham
Looks like a good fix from here!
In a similar vein, The studs also go into the ater gallery and rely on sealant on the thread.
Well.
Car is back running. Head refurbished, fitted, engine run and is re torqued. Compression test shows all between 110 - 115.
No leak down test done (wish to perform this so will look for a test kit.)
Result. Runs exactly the same as it did when it had a blown head gasket and still smokes like a train. 100% effort. 0% reward.
Embarrassing to say the least. : (
Graham.
So you sealed all the seven studs that pass through the inlet tract?
What state are your wicks in the rockers?
If you run the engine with the rocker cover removed can you see excessive oil flow from any of the rockers where they hit the valve stems?
Peter
Graham, the valve stem seals you have fitted look to be just a rubber ring
under the collets . Have the valve guides been machined to accept
another type of seal ?
Peter B.
Although if the wicks haven’t been done,it is more likely they’ll be blocked and not enough oil getting to the tops of the valve stem.
Which is also a problem.
Sorry to hear continued problem.
If smoke at cold start, be sure to be aware of steam produced which will show condensation trail out tail until exhaust is warm.
If smoke is due to too rich mixture, then carbs indicated.
If smoke is oil based, look at oil flow on top of head with rocker cover off. One way to see if oil is coming in through the valves is to disconnect the oil feed to the head, plug incoming line with a cone like a pencil (easy to hold in place), and run the engine a few tens of seconds while watching smoke level. A squirt of oil from a can down each pushrod before the oil-free test may calm your nerves about tappet lubrication while not supplying oil to the top end.
Is the fuel pump mechanical or electric?
One often finds a little oil smoke { light grey] from the LH ex pipe at start up. The engine slopes to the back and when left sitting, oil around the valve gear etc will congregate at the back where the #1 inlet valve lives And seeps down until next time it’s started.
The petrol pump {s] are electrical. two at the front, and helpful to have another at the rear.
We’ve always used K line inserts in the valve guides as they have closer tolerances than the originals
There should be oil pooling on the valve spring retainer,but most of this won’t get to the valve guide, There should be buckets of it running down the pushrods.
When the rocker shaft and rockers were rebuilt were two bronze bushes used per rocker…I recall much wringing of hands many years ago when someone used a single long bush instead of the two and the oil holes were blocked off. Leading to expensive sounding noises.
Originally the row of studs that come through the inlet tract had nuts with alloy caps to seal the threads off from oil seepage. Sort of like a dome nut.
they are very inexpensive on Ebay
that is definitely what I would do
especially as you mention the engine had poor work done at some time that involved pistons
have a very smoky 4.2 to pull down when I get around to it, was supposedly re-ringed before me
Hi Peter.
The wicks were replaced some time back at the same time I replaced the worn rocker shaft.
I will confirm if the appears to be over oiling but if there was the introduction of the seals under the collets was to form an umbrella over the valve stem and reduce the amount of oil running down them.
I intend to refit, if possible, valve stem seals on the inlets.
Some more investigating today some based on info members provided.
There appears too much oil is in fact getting into the rocker cover.
Not at the valve (wick) ends but from several rockers on the pushrod side.
A steady stream of oil pouring from several at idle or is this normal?
I have confirmed the oil pressure several times and it certainly isnt high.
So what controls the amount of oil supplied to the rockers?
There seems to be no restrictions and can flow at will from the pushrod side of the all the rockers at engine oil pressure.
Regards, Graham.
Hi Graham,
There is no control (other than orifice size ) of the oil supply to the rocker shaft. In the original design the feed holes to the rockers are located under the rocker bushes nearest the pillars and there is a small 3 thou flat machined longitudinally on the shaft from the feed hole to a corresponding position under the neighouring bush. This arrangement gave a small amount of restriction to the oil flow at each rocker.
However certain replacement shafts deviate from this design. The feed holes in these shafts have been moved so that they
correspond with the gap between the two bushes of each rocker. The result is that the oil feed is much less restricted. This very noticeable on the push rods. Each push rod is absolutely flooded with oil, its cup overflowing on all sides such that the oil totally envelopes the rod.
The effect of this largely unrestricted flow is a significant loss of oil pressure.
The wicks restrict the flow to contact area of rocker and stem but there is another smaller diameter hole that feeds oil to the push rod.
It would be worth checking whether your shaft has the little flats and the correct positioning of the feed holes under the bushes adjacent to the pillars.
Peter
Mark V’s have a single LCS (Large Capacity Single aka square body) SU electric fuel pump located under the car on the chassis, so below the fuel tank level.
The head nuts under the rocker cover should have plain flat washers, not split lock washers, and reasonably free of scratches and other damage that would reduce their sealing effectiveness.
I seem to recall also that it was possible to put the head studs in upside down, such that the threaded end would protrude up too far out of the head and would push the little aluminum covers off the nuts as you tighten them.
There’s the answer for the over oiling and probably lower than normal oil pressure.
Yes mine does have a replacement rocker shaft that does not have flats on it as the holes do indeed line up with the gap between the bushes allowing unrestricted flow out the pushrod end of the rockers.
Not quite sure how I will address this but that’s excellent. Something to work with. Thanks. Most appreciated
Mental note.
We work damn hard on our cars to keep them in good running condition however with some replacement parts (in my case a head gasket and altered rocker shaft) and shoddy professionals workmanship we are introducing problems that are quite unnecessary.
Not sure what the answer is.
Regards, Graham.