Problems with engine - water loss

[rogerk]

Hello all
with the overheating of the engine on the way to the National weekend and the return journey in which I was loosing water in the buckets full I have been trying to annalyse the problem

No water in the oil
No oil in the water
No obvious signs of water loss
looks like it keeps flowing out of the expansion overflow pipe
Removed the thermostat and now the engine only gets to halfway up the gauge but still lossing water
Fitted a new 20psi pressure cap

Checked the pressure of the cooling system and holds 20Ppsi with no loss in pressure over 5 mins

Checked the pressures of each cylinder which was 130psi on each cylinder
BUT
after speaking with Stagmuffin I did the readings the wrong way
So this morning I took out all 8 sparkplugs and took the readings of each cylinder in turn by holding the throttle open and my wife turning the ignition for 5 secs

first reading second reading after two shots of oil added to cylinder
cylinder 1 100psi 110psi
cylinder 2 95psi 110psi
cylinder 3 100psi 115psi
cylinder 4 105psi 125psi
cylinder 5 100psi 130psi
cylinder 6 105psi 125psi
cylinder 7 95psi 105psi
cylinder 8 105psi 125psi

I know the readings are low but wondered if the head gasket has gone would that be where the waters going and explain the low compression readings
The car seams to run well and pulls away fine with no miss fireing
any ideas would be appreciated

rogerk

[sjm]

Air Lock ? Another member had the same thing happen a couple of years ago.

Steve

[ChasR]

I would not necessarily say that your HG is gone with those readings from what you have said. Have you checked your voltage stabilizer is connected and that the earth going to the back of the speedo is satisfactory (the latter for me was an issue with the wiring needing to be cut back and remade).

One way to check the HG is to either use a sniffer test in the expansion bottle to see if you have an issue or to use an exhaust gas analyser in the expansion tank checking for emissions in there (there should be none).

Other members may well say this, but taking out your thermostat may not help your overheating issue with it allowing hot water to go back into the engine via the bypass hose (assuming the right thermostat with the foot is fitted).

[flying farmer]

If the cooling system is pressurising and it is throwing water out of the overflow then I am afraid it is head gasket failure. It only requires a very small leak through the fire ring into the cooling system for this to happen, due to the much higher pressures in the cylinders compared to the cooling system.It is rare for water to get into the cylinders unless the engine has boiled badly leading to bad head warping.
If you haven't tried it yet, retorque the head bolts with the engine cold. Slacken each nut/stud by half a flat before retorquing, sometimes the torque figures are very low due to the head gasket compressing with age, and a retorque may solve the problem. Do not exceed the recommended figures as I have come across blocks distorted by overtightening.
Most of the time the compression figures will not show up a failure in its early stages, however, in my experience, the gaskets normally fail at the back of the rearmost cylinder on each cylinder bank, so it is possible that cylinder 7 is the cause of the trouble.
The gaskets eventually fail due to fatigue due to the different expansion rates of the iron block and alloy heads, it will always happen, but the length of time between failures can be extended by using good quality gaskets and regular maintainance.
The first Stag engine I built lasted 70,000 miles using a pair of cheap gaskets form a large well known supplier. On stripping the engine, both rear cylinder fire rings had failed. The engine had never been overheated, and both the block and the head faces were flat and a new pair of gaskets (better quality) solved the problem.
Do look out for warped blocks though. My current efi stag came with a history file that included three head gasket changes in 50,000 miles. The head faces were perfect but the rear of the block had an 8 thou warp/corrosion problem which was the probable reason for the repeated failures.
As to the low compression figures, since they are all fairly even it may simply be a case of low compression pistons and thick gaskets fitted to an engine which has had very little skimmed off the heads.
Neil

[martin]

Hi Roger, could the water be coming out from under the brass ring below the pressure cap, occasionally they work loose. Martin.

[rogerk]

thanks Flying Farmer for the reply
The engine was rebuilt just before I brought the car at 41k and it has now completed 62k and I have own it for just six years
The car has had a checkered history of owners but not too much detail history over 15 years ago
will be checking for gasses in the water tomorrow

rogerk

[rogerk]

Air Lock ? Another member had the same thing happen a couple of years ago.

Steve

Hi Steve
I have made sure every time I have filled the radiator the slopes up with the radiator at the highest point and fill up via the brass plug
rogerk

[rogerk]

Hi Roger, could the water be coming out from under the brass ring below the pressure cap, occasionally they work loose. Martin.

Hi Martin
It does not look like it is leaking from the ring
Rogerk