S2 #378 (Steve) - hopefully only light fixes

[nube5]

The bulb faces inward - that is it goes in the housing, not the hose connector

Thermostat.jpg (20.46 KiB) Viewed 14656 times

[Simon_P]

bulb outwards

Do you mean that?

What coolant mix are you using? What is the level when cold and bled?
What is the temperature indicated on the gauge a. When the thermostat opens. B. When the fans come on?
When do the bubbles start?
When part warm is the top hose squashy or firm?

[378S2]

Hi Simon

I meant that the thermostat is correctly fitted.

- I’m using 25% premix (standard here, cold isn’t a problem but hot is)
- level when cold and bled is to the correct mark, higher when the air is there.
- I think they don’t get started until the engine is warm, hard to be precise on that one
- I’m not too sure if squashy or firm, not at home now to check it but I understand the question - ie is there air in there or not?
- The thermostat opens just before 1/4, and the fans a little past 1/4 (it is fitted with one of the lower temperature switches, I haven’t been able to exactly characterise it but I think it is a 92/97C).

Speaking to James at SJS, I think I know which club I’m about to join. Once the leak down test kit arrives I’ll know for sure. He says that the sniffer tests are unreliable.

For the Blackadder fans out there: I made a note in my diary on the way over. It simply says... “Bugger!”

[Simon_P]

- I’m not too sure if squashy or firm, not at home now to check it but I understand the question - ie is there air in there or not?

No. The test is to see if If gas from the cylinders is pressurising the cooling system.
Also, coolant leaking into the cylinder will clean off the carbon.
The leakdown test might be inconclusive as you can't seal the rings, but I suppose you may see bubbles in the coolant.

[378S2]

Ah, ok I see. Now I did try the ‘chicken test’ whereby I put a glove on the open filler cap with a zip-tie to see if it would inflate, but I didn’t rev it highly, which in hindsight would mask an early failure if there is one since it would be close to idle and not under boost.

James’ advice was that my next step is to put 150psi in using the leak down and see what happens - if bubbles come up then it’s conclusive. So I will report back once I’ve done that. Until then I’ll refurb the front brakes to take my mind off it.

The handbrake is working beautifully now, which is very little consolation!

[378S2]

My $30 leak down test finally arrived, and it’s junk! The 14mm adaptor came off the hose, but worse was the cheap and rough thread which I refused to let near my spark plug apertures.

I popped round to a friend who’s got a MIG and welded an air line fitting to the steel part of a spark plug, with the centre removed. So finally a diagnosis is not far away.

[TorqueHorse]

The 14mm adaptor came off the hose...

Finds a leak every time, guaranteed!

[dapinky]

You've got the same type of steel-toed safety footwear that I use!

(and my motto with welding is if it stays solidly attached and doesn't leak, it's a good weld.)

[378S2]

The bulb faces inward - that is it goes in the housing, not the hose connector

Thermostat.jpg

Thank you, that’s how I fitted it, I was getting my terms the wrong way round, but fortunately the thermostat is fitted per the instructions.

[378S2]

Ok the internet. I need you!

With the spark-plug-adaptor I’ve done my leak down test... and they all look pretty good. Noting that this is most definitely the cheapest test set the internet has to offer, to my mind the readings all look within bounds?

I had some problems setting the cylinders to TDC and keeping them there, so my method was to connect each cylinder to the test set, and then turn the crank with a ratchet until it pressurised and snap a photo of the dials. The engine was warm, but not hot.

Can anyone think of anything else that could be causing the bubbles? Is there anywhere else where pressurised gas and coolant come close to each other?

I will attempt the full pressure test tomorrow, it needs a helper to put their foot on the brake. That’s the one SJS recommends, perhaps if it is a very small leak then it will only present itself at the highest pressures?

If I’m being a hypochondriac then I’ll be a very happy man!

[Fredjohn]

Am I missing something, but aren't the arrows (the business end of the needle) pointing to high leakage?

[378S2]

Am I missing something, but aren't the arrows (the business end of the needle) pointing to high leakage?

No, they’re pointing to (almost) zero leakage. Leakage is measured in %, anti-clockwise on the scale. ‘Low’ means low leakage which is why it’s green. You calibrate it to ‘0’ in the yellow segment with nothing attached and zero air escaping, then connect to each cylinder.

[Fredjohn]

Am I missing something, but aren't the arrows (the business end of the needle) pointing to high leakage?

No, they’re pointing to (almost) zero leakage. Leakage is measured in %, anti-clockwise on the scale. ‘Low’ means low leakage which is why it’s green. You calibrate it to ‘0’ in the yellow segment with nothing attached and zero air escaping, then connect to each cylinder.

Are you sure????

You have about 95psi on the left gauge, indicated by the arrow, which I believe is the normally required test pressure. Therefore surely any loss reading will also be indicated by an arrow. Just like a compass needle arrow points North, but the tail points South.

[378S2]

Yes, sure... although I’m going to triple check it now in the morning anyway. That being said, I have been wrong plenty of times in the past! I’ve got a compression tester on loan so I’ll do that too.

But the instructions are clear;

1. Connect the air supply but not the cylinder adapter
2. Adjust the regulator to set the leak gauge to 0% (full scale). It notes this is typically between 20 and 30 PSI
3. Set to TDC, connect the cylinder adapter and take a reading.

With the adapter connected but not screwed in to anything you get a 100% leak.

[TorqueHorse]

Wait, now I'm confused. Isn't the 'arrow' at the end is just the counterweight, and not the indicator end? 'Tails' don't usually go past the numbers on a dial scale, if they are tails. Oh no, I'm feeling deja-vu about being confused in reading analog measurements again

[378S2]

Am I missing something, but aren't the arrows (the business end of the needle) pointing to high leakage?

So sorry FredJohn, I hadn’t noticed the ‘arrow’ on the opposite side of the needle until TorqueHorse also asked about it, and now I understand your question. My read of the dials is that it is the long end that does the measurement, and the short end is a confusingly designed counterweight.

Wait, now I'm confused. Isn't the 'arrow' at the end is just the counterweight

Yes I see what you mean, that is the tail, doesn’t help that it has a pointer on it! I hadn’t noticed because I’ve been watching them move and it’s pretty obvious then because when zeroed the both sit exactly where you’d expect. I suppose you get what you pay for, and this only cost me $30!

I’m going to do it again today, I don’t like the way I was finding TDC, and I didn’t pull off the various hoses caps etc like you’re supposed to (was doing it in a rush while the kids were in the bath). I’ll find an hour today and do
It properly.

Fingers and toes crossed please that I am just finding problems where none exist and I can get back to thinking I look cool cruising about in jt!

[esprit888]

Its very hard to diagnose a barely leaking cylinder head gasket with a leak down tester unless its totally gone to a point that it would be very noticeable when driving (like its running on 2 or 3 cylinder) This is because you are only using around 30 PSI and the Elan has a Compression ratio of 8.2:1 so its compression ratio/combustion pressure is 120 PSI (even more under boost). On some compression testers you can remove the schrader valve and use this hose to test full cylinder pressure. If you can remove the schrader valve then first make sure the cylinder to be tested is at TDC on the compression stroke, plugs are tight in the other 3 cylinders, car is in gear and someone has their foot on the brake or wheels are chocked securely. Hook up the hose to the plug adapter and screw it in then open your air valve to give 120 PSI (or whatever your compressor can manage) directly in to the cylinder. There will be some leakage past the rings but it should be minimal, if you hear it it in the intake or exhaust you are not on the compression stroke (or you have valve problems, and that's a whole other issue ) Check for bubbles and repeat for each cylinder. One thing to note is that the actual pressure during the moment of ignition of the fuel/air mixture is exponentially higher than the CR, there are a number of variables but in the case of a forced induction system such as the M100 it will be in excess of 1,000 PSI.

[378S2]

Got it - thanks. Ok I’ll enlist a helper and do that as well then.

[Fredjohn]

Yes I can see it now too, the arrow is a counterbalance, not a pointer. Very confusing.

I stand corrected.

Good luck with your diagnostics, hope you sort it.

[378S2]

Thanks Fred John, really hope to get time today. The Snapon one is a delight, but a lot more expensive and I really cannot justify snapon tools on my budget!