25-06-2023, 10:30 PM (This post was last modified: 25-06-2023, 10:31 PM by JoshDoran.)
Hi all,
First time posting here and looking for some help.
Working on my Grandpa’s 1937 Austin 7 Opal but the engine is not original and had a few things added over the years. The base of the spark plugs were bubbling slightly. I have them a tighten so see if that helps.
Otherwise, any suggestions? Current thought is the head gasket might be seeping water in. Maybe Radweld to plug any gaps?
Water around the spark plugs can arise from leakage through the central hinge of the bonnet from rain or washing the car. There is a channel which connects the front grill to the back of the engine bay - see photo- which will collect the leakage and direct it away from the engine. If there are holes in the channel as a result of fittings being removed, water will drop in. I had some holes which I temporarily blocked with blutak.
The bubbles are likely to be the result of the washers on spark plugs not making a good seal.
If photo is upside down, click on it to correct that.
26-06-2023, 07:22 AM (This post was last modified: 26-06-2023, 07:29 AM by Andy Bennett.)
There isn't a 'seeping' direct route from a failing head gasket for cooling water to come through the spark plug hole other than via the cylinder itself and if that is the route then best not run the engine as a cylinder filling with water is going to end badly for the engine under compression. You would also know quickly as you probably wouldn't be firing smoothly on all cylinders. It is more usual to see bubbling around a head stud as the sign of a leaking or failing gasket as there isn't much gasket between some of the water ways and their closest head studs.
If it is just water dropping onto the engine then the bubbling might well be it simply boiling off as the engine warms very quickly here.
A quick removal of the offending spark plug and a look down the bore will give you first indication of whether or not you have a major problem, then compression testing of the cylinders will show you if you have any variability and so possibly a failing gasket. This is a good test to do anyway if you are in effect running a car that hasn't been used for a while.
Oh and welcome to the world of Austin Sevens. It sounds as if you may benefit from joining your local club and asking a friendly member to give the car a look over.
I had this problem with a Ruby a little while ago.
It turned out the champion spark plugs had a bevelled edge which did not seal properly!
After changing the plugs for a flat sealing edge no further leaks.
Can’t remember which plugs gave this good seal (not at home to check)
But recommended by the Green Spark Plug Company
I can confirm the plug type later this week.
Regards
Tim
Interesting topic and always good to know that answers and solutions can be found in this forum so quickly.
One question... Andy says "A quick removal of the offending spark plug and a look down the bore will give you first indication of whether or not you have a major problem, then compression testing of the cylinders will show you if you have any variability and so possibly a failing gasket"
What can be seen? Rust? A gap in the gasket?
I also had "moisture" around the sparking plug and it did not seem to be water, but a more oily, petrol-like liquid. I guessed that it was the sealing of the plug but it is always good to know more about other potential catastrophes as well.
Kind regards
Frank
Hi Frank
I was just suggesting that if water is coming from inside the engine out through the spark plug hole then it is likely coming via the cylinder (unless I guess theoretically the spark plug thread itself has failed through to the water ways but don't know if that actually happens).
Given the info we have I am not sure it is the most likely source, as lots of water (whether through a failing gasket or block etc) would of course be causing lots of other running problems and would likely be white 'smoke' at the very least and falling radiator level etc.
However, it is easy to do a first check by simply looking down the cylinder to see if there is water there from a slow seep via the gasket and then doing a compression check across the 4 cylinders to see if there is significant variation and so a potential problem with the gasket or worse etc before taking the head off. You won't see the gasket, but you might see any impact from its poor health.
If Josh finds nothing visually wrong and relatively even pressures then in my mind it is unlikely to be coming from inside the engine. In my mind the seating of the spark plugs is secondary, since even if they are not 100% sealed the water simply shouldn't be in the cylinder to be pushed out there anyway and so a poor sealing spark plug might be revealing a problem.
Noting of course perhaps the most likely simple scenario that water has simply dropped down as suggested and is boiling off.
What it definitely isn't is a radweld situation and some quick checks now and perhaps a call on a local experienced owner might save a simple problem becoming a catastrophic one or hopefully reassure that all is well.
All this from my relatively inexperienced knowledge base. But I did have a head gasket fail once with resulting water into a cylinder, and I knew about it pretty quickly and am glad I immediately switched off the engine, as of course water doesn't compress well and I have a feeling I would have been in the market for a new crank or more.
