I Think I Killed It

[Ducked]

Originally Posted By: mk378
Not necessarily. It should say "DO NOT ADD WATER" somewhere on it. Even where I can read all the words, the difference isn't always super clear. You could also test it with a hydrometer.

If you fill up with 100% concentrate and then get on the freeway, you're going to have a bad time.



I'll try and check. Actually quite hard to find the SG of 100% ethylene glycol (assuming that's what it is).

According to

ww.alfaowner.com/Forum/alfa-gtv-andamp-916-spider/157080-specific-gravity-of-ethylene-glycol-coolant.html


“Looking at Texaco spec sheets, raw is about 1.12SG at 15.6 deg C. Is the SG scales relationship with temperature linear? Temperature compensated to 20deg C”


http://www.newtonnet.co.uk/coupe/service/webtech/iindex.asp@id=12106

Shows 50% EG at 20C as 1.082

I have a battery hydrometer I bought when I was recently in the UK. Havn’t used it yet, and don't have it handy but

http://www.freeasestudyguides.com/battery-specific-gravity-test.html

shows the reading range of a battery acid hydrometer as 1.1 to 1.3

So if its in the reading range, its concentrate, and if its below the reading range its probably diluted.

 

[Ducked]

Originally Posted By: Silk
I had a Charade Gt Ti...100hp, 1,000cc, it was a little rocket. A bit of a stealth package too, discrete body kit and wheels. Keeping them cool is an ongoing chore, they run hot. I was talking to a guy who used to rally one here - they used up to 60psi boost and never lost an engine.


Tried that and there wasn't (to me) a clear indication that it was pressurising.

I then ran it for a while (maybe 10 minutes) with a funnel in the radiator cap. This time it didn't seem to blow any bubbles until I switched it off, and I suppose that might have been local boiling at a hot spot, but it did seem to expand more, almost filling the funnel (see faint tide mark in first photo). I'd guess this much expansion might imply there is still quite a lot of trapped air in there.

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After I turned it off, it took quite a while to contract again, and left quite a lot of sediment. I wonder if it would be worth draining it again and letting this stuff settle out, assuming it doesn't include anything useful, like anti-corrosion components.



One of the three bolts in the exhaust flange is missing, which is probably why its blowing. Access is worse than it looks in these pictures, since that corner of the flange is up against the front engine mount.



The empty bolt hole is in shadow, on the left of the picture.

 

[Ducked]

Looks like I've lost/had stolen quite a lot of my tools, which will cause a bit of delay.

I have to work in public areas, and since things don't tend to get stolen much here, I've got relatively casual about packing things away (much more than I was, or could have been in the UK), sometimes even leaving tools in the car overnight.

I just stopped getting away with it.

 

[Ducked]

Fitted a home-made exhaust gasket which seems to be holding from a 20k or so test drive, though I didn't go above 80 kph

There was some sign of coolant loss from the overflow reservoir overflow, so I'm still not sure about the head gasket.

I'll fit an overflow bottle so I can monitor (and conserve) loss, but I think I probably need to pressure test the cooling system.

Never really thought about the rad cap properly before, but as far as I can tell, I ought to be able to pressurise the system via the overflow hose.

If I want to monitor the pressure loss I'll have to add a schrader valve so I can put a tyre guage on it.

Am I missing anything?

http://www.are.com.au/images/import11.jpg

 

[Jetronic]

no, you got it right. but don't forget pressure and temperature are linked in a closed system.

 

[Ducked]

Originally Posted By: Jetronic
no, you got it right. but don't forget pressure and temperature are linked in a closed system.


That's a bit strange then. A bit of googling shows some gadgets for this job, which are fairly expensive, and don't test the radiator cap either.

There are also some noble DIY efforts which replace the radiator cap with a home-made plug.

As far as I can tell this is all completely unnecessary.

Re your temperature/pressure comment, not sure I get your point. Although temperature and pressure are related, it seems to me that pressure is still just pressure. IOW 15 psi is the same pressure at any temperature.

It does seem possible that, due to thermal expansion, the engine would leak differently when hot, and of course the differential between combustion chamber pressure and cooling jacket pressure is much greater, and in the opposite direction, so pressurising the cooling system doesn't accurately mimic what's happening in a running engine.

Might still be informative though.

Attempting to measure over-pressurisation in a running engine, OTOH, sounds a bit risky and complicated by the temp/pressure relationship, (maybe that's what you meant?), and for that you might have to substitute/replace the pressure relief cap.

I suppose you could measure the volume increase and/or volume of gas produced at atmospheric pressure, but the thing will start to boil after a while.

Or you could measure the volume of liquid (already done) and/or gas that goes via the overflow. Maybe an inverted cup arrangement to catch bubbles?

I have some indication of what seems a high and early volume increase into a funnel, but I don't have a "known good" control to help me interpret it.

 

[mk378]

Your head gasket is probably OK. If it leaks, there is a tendency to displace coolant out of the engine and radiator into the reservoir bottle, eventually overflowing it. This then leads to overheating due to lack of coolant where it is needed in the radiator and engine.

One quick test is to fill up and close up the system, start the engine cold and rev it while feeling the pressure in the top radiator hose. It should stay soft with no pressure until the engine has warmed up substantially.

Really, again, you're severely overthinking this. Of course if you like working on cars in monsoon weather and fabricating homemade parts, keep at it. Most sane people would have bought a newer/better car a long time ago.

 

[Ducked]

Originally Posted By: mk378
Your head gasket is probably OK. If it leaks, there is a tendency to displace coolant out of the engine and radiator into the reservoir bottle, eventually overflowing it. This then leads to overheating due to lack of coolant where it is needed in the radiator and engine.



Since this seems to be happening, a bit, I'd say the "probably OK" probability might be less than 0.95 at this time.

 

[Ducked]

Originally Posted By: mk378


Really, again, you're severely overthinking this. Of course if you like working on cars in monsoon weather and fabricating homemade parts, keep at it. Most sane people would have bought a newer/better car a long time ago.


Yeh, that'd work as a general philosophy:-

Maintenance Issues : Buy Another Car.

Lubrication Issues : Follow The Manufacturers Recommendations

Both the above, and Everything Else: It Doesn't Matter. STOP THINKING.

I hereby declare this forum closed to most sane people.

But perhaps that isn't the target demographic?

 

[andyd]

Ducked, don't despair. The head guru at the Ranger site says to tie a rubber glove onto the neck for the pressure cap. If it inflates and dances, it has been pressurized with exhaust. Better a car with known problems than a new(er) car and unknown problems.

 

[Ducked]

Originally Posted By: andyd
The head guru at the Ranger site says to tie a rubber glove onto the neck for the pressure cap. If it inflates and dances, it has been pressurized with exhaust.


Ah...I was planning something a little more...er...elaborate, but that'll be quicker and...er...more elegant. Thanks for the tip.

 

[Ducked]

Compression test wasn't very informative, but then I didn't expect it to be, especially since I have the wrong adaptor for it and can only use the push-on cone.

Cyl l: 145, 150, 145
Cyl 2: 160 170, 120 (cranking slower due to battery low)
Cyl 3: 170, 160

Plug appearance showed marked bilateral asymmetry, which I havn't noticed before. Don't know how the plugs are oriented in the head (I'll mark them) but I suppose this could be ingested coolant cleaning one side. I've suspected its been running rich since I cleaned the carb, though, so it might just be that.





First attempt at a coolant system pressure test was inconclusive too, since the radiator cap wouldn't hold pressure.





I might break down and try and get a new radiator cap tomorrow, but I'm unconvinced this is the (or a) problem since the outer radiator cap doesn't see pressure in normal use.





Some pressure was getting into the system since I could feel and hear it releasing when I took the cap off, but of course I couldn't measure it.

To do that I'll probably have to make a separate pressure cap, though I might be able to base it on the existing one..

 

[Vikas]

Quote:
since the outer radiator cap doesn't see pressure in normal use
what makes you say so? It is designed to hold that pressure. If it does not, the coolant will boil over. By pressurizing the boiling temperature is increased and thus it is prevented from boiling under normal operating condition.

 

[mk378]

True, the top seal isn't designed for pressure beyond the tiny amount to push the coolant into the tank.

Why are you still trying to do your complicated test when two very simple tests have been mentioned here?

 

[Ducked]

Originally Posted By: mk378
True, the top seal isn't designed for pressure beyond the tiny amount to push the coolant into the tank.

Why are you still trying to do your complicated test when two very simple tests have been mentioned here?


Pressure testing of the cooling system is one of the recognised tests for head gasket problems, and if I can get it to work, MIGHT be more sensitive

Simple test1 would, I take it, be pressurisation of the radiator hose. As I said above, I didn't detect such pressurisation but I'm not sure I would recognise slightly abnormal pressurisation anyway.

Simple test2, would, I take it, be the "rubber glove test". I might try that tommorrow, but I'm not sure that it's very different from watching for bubbles, which is apparently often inconclusive.

A variant of that which might be more informative would be trapping gassing into the coolant tank, since that could be left in place during normal running of the engine. Might try that tomorrow as well.

 

[Ducked]

Originally Posted By: Vikas
Quote:
since the outer radiator cap doesn't see pressure in normal use
what makes you say so? It is designed to hold that pressure.


See diagram on page 3 above.

 

[Ducked]

To misquote Henry Folland, "simplicate and add airtightness". I simplicated a bit and added some airtightness, but maybe not quite enough.

My first attempt to stop the rad cap leaking with RTV was unsuccessful, so I tried a rubber bung from a lab supplies shop. 20NT. I didn't have a cork borer so I used a piece of arrow shaft with cuts in it. The hole is off-centre because I was planning on having one for a bicycle pump and another for a guage.



Instead I used the overflow port for the guage, and my cheapo Mityvac substitute enema syringe (also bleeds brakes) for the pump.

.

Fully compressed, the syringe gives just over 10 psi, bit lower than operating pressure but FSD on the guage anyway.





"Somewhere" I've read 20% pressure loss in half an hour as the suggested criteria for diagnosing a leak. This rig showed about 4X that (40% in about 20 mins) so I've got a leak, but it might be in the apparatus rather than the car.

One further possibility for "simplicating and adding more airtightness" would be to get a smaller bung which could seal where the rad cap does, (eliminating the overflow from the system) and combining the pump and the guage so theres only one hole in it.

The syringe can also act as a guage of sorts, since uncompressed it "rebounds", though it doesn't rebound all the way, and maintains about 1.5 psi unloaded.

"Rebound" syringe at T=0



"Rebound" pressure at T=0



If I'm still losing pressure, I could perhaps try to factor out leakage from the apparatus by sticking it in a partly water filled bottle, which could be assumed not to leak, so any excess of car v. bottle would be down to the cooling system.

 

[andyd]

I doubt you can use a bung and achieve 15 lbs of pressure. At this point I would drive it gently whilst looking for alternate transport. It may surprise you. I would carry a gallon or 2 of coolant just because.

 

[Ducked]

Originally Posted By: andyd
I doubt you can use a bung and achieve 15 lbs of pressure.


As stated above, it achieved about 11 psi, and the gauge scale only goes up to 10.

With this setup I'd say the limiting factor is the volume of the syringe rather than the airtightness of the bung, perhaps just as well since there's no pressure relief to prevent you damaging the system.

 

[mk378]

When the engine is running there is very high pressure in the cylinders which can force its way through even small leaks in the head gasket. Any serious test of the head gasket is done with the engine running while looking for gasses (especially CO2, which is a distinctive product of combustion) to appear in the cooling system.

Pressurizing through the radiator while cold is good for looking for leaks to the outside such as bad hoses or cracks in the radiator. Head gasket not so much.