britishtrident
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| posted on 1/6/13 at 06:08 PM |
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This is a long thread to read back through so I take you are 100% sure on the gauge accuracy ?
Only other things left are ignition timing excessively retarded or a leak, small steam leaks are invisible and the only way to track them
down is a cold pressure test.
I pressure test using home made tester based on a design found on the web for a cylinder leakdown tester, it has two gauges with a restrictor when
up to pressure between them any difference in reading between the gauges indicates a leak.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Ben_Copeland
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| posted on 1/6/13 at 06:19 PM |
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Megasquirt was setup on a rolling road by Matt @ Mtech. Fairly confident that he knew what he was doing but i'm guessing its definately worth
checking.
Where would you test on the coolant system ? Between where and where?
Thanks
Ben
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britishtrident
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| posted on 1/6/13 at 07:09 PM |
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A leakdown test just tees into the small bore hose between the header and top of engine, it is surprising how many hidden leaks it will show
up.
Three times mine has picked up leaks that had been misdiagnosed as head gasket failure.
A restrictoris fitted between the two gauges. Take the pressure up to rad running pressure and and after a couple of seconds any difference between
the two gauge readings will tell you have leak which you should also be able hear or see.
The best way to check radiator flow is disconnect the top and bottom hoses and fit a garden hose into the bottom hose,with the garden hose on full
flow if water pours out the top good style all is well.
[Edited on 1/6/13 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Ben_Copeland
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| posted on 1/6/13 at 07:16 PM |
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Thanks mate, The rad is fine, i've flushed everything through with a garden hose.
I think i get the way that tester works. basically your pressurising the system, what sort of pressure do you usually put in?
Ben
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britishtrident
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| posted on 1/6/13 at 08:12 PM |
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quote:
Originally posted by Ben_Copeland
Thanks mate, The rad is fine, i've flushed everything through with a garden hose.
I think i get the way that tester works. basically your pressurising the system, what sort of pressure do you usually put in?
Just short of the pressure cap rating -- usually on the MG-Rover stuff I work on 1.4bar/20 psi
Even a slight leak will show up as a 2psi difference. A smaller hole in the restrictor will give a bigger difference between the two gauges. I
just used a mig tip because it was easy and what the plans for the DIY cylinder leakdown tester I copied it from used.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Ben_Copeland
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| posted on 1/6/13 at 10:27 PM |
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OK thanks, i'll have a look at making one.
If i do find a pressure drop how the hell do i go about finding the leak lol
[Edited on 1/6/13 by Ben_Copeland]
Ben
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dave_424
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| posted on 1/6/13 at 10:35 PM |
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Soapy water in a spray bottle, spray around the engine and should see bubbles where the leak is. If it is a leak of a good size you will hear it as
well.
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Ben_Copeland
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| posted on 1/6/13 at 10:54 PM |
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quote:
Originally posted by dave_424
Soapy water in a spray bottle, spray around the engine and should see bubbles where the leak is. If it is a leak of a good size you will hear it as
well.
Ah of course...
Thanks
Ben
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britishtrident
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| posted on 2/6/13 at 07:59 AM |
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This is from Wikipedia
Sealey sell similar tester but they cost too much.
Usually you can also hear any leaks.
[Edited on 2/6/13 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Ben_Copeland
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| posted on 2/6/13 at 09:27 AM |
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Well I've might not have all the bits , but I have got a compressor with regulator so I might try connecting that on and just seeing if I can
see/ hear any leaks before making a leak down tester.
Thanks you for all the info, wish this was easy!
Ben
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Ben_Copeland
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| posted on 2/6/13 at 03:42 PM |
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Not had time to make a tester, but I did tee in an airline @ 20psi. Water leaked from the top hose between rad and thermostat.
Could that of been causing overheating? I've wacked a second jubilee clip on the pipe and its stopped the leak. That was the only one that was
appearent.
Got to get a new sump before starting it so won't know till next weekend.
Ben
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mike2704
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| posted on 2/6/13 at 04:00 PM |
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overheating
Hi common fault with these is the inner water pump fins spin on the center shaft, looks ok when u check the flow but when it gets hot its worse.
you will have to take the pump out to check.
Hope this helps Mike
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Ben_Copeland
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| posted on 2/6/13 at 04:08 PM |
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quote:
Originally posted by mike2704
Hi common fault with these is the inner water pump fins spin on the center shaft, looks ok when u check the flow but when it gets hot its worse.
you will have to take the pump out to check.
Hope this helps Mike
It's had two water pumps mate. So I doubt very much this is the issue.
Ben
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Ben_Copeland
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| posted on 6/7/13 at 04:09 PM |
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Bit if an update.
So now I've changed head gasket and cylinder head because the head gasket blew on the motorway.
Basically nothing but the ECU, pipe work and car is left.
New bottom end, new cylinder head, new thermostat, new fan switch, new water pump, new radiator, raised water bottle, pumped 20 psi into system and
find a tiny leak.
The radiator is just not getting hot enough to turn the fan on, this is ridiculous.
Ben
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rdodger
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| posted on 6/7/13 at 05:15 PM |
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Just to recap.
It doesn't overheat when driven gently?
It does overheat when driven quickly?
Does it over heat when sat at idle?
There is no flow from the radiator bleed?
If that is correct then the fan coming on isn't the issue as it won't help at all when you are moving. Even at modest speed there should
be much more air flow through the rad than any fan could manage.
It seems to me that there just isn't enough flow through the rad. Surely there should be a good flow through the rad bleed back to the header
tank?
Are you 100% sure there is no air in the system?
Are you 100% sure that the water pump is working?
Last one. Can you lay your hands on/ borrow an electric pump and plumb that in to see if things improve?
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Ben_Copeland
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| posted on 6/7/13 at 05:38 PM |
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That's all correct.
It overheats when idle.
Got a 16inch fan now and that cools the engine a little if its wired on all the time.
It's definately a flow problem.
Don't know anyone with an electric fan unfortunately.
Ben
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rdodger
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| posted on 6/7/13 at 06:10 PM |
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Well as I see it then it's one of 3 things
1, The water pump isn't working properly
2, It isn't plumbed correctly.
3, There is an obstruction somewhere.
I know you have been through this but ......
...when you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.'
Sherlock Holmes
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Ben_Copeland
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| posted on 6/7/13 at 06:20 PM |
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1. Brand New Pump x 2
2. Plumbed as per SBD's well used guide
3. Everythings been flushed and theres no obstructions in the pipework/radiator. I doubt very much 2 blocks and 2 cylinder heads have the same
blockage.
Ben
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rdodger
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| posted on 6/7/13 at 06:43 PM |
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Why is there no flow through the radiator then?
Did you try a clear length of hose?
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Ben_Copeland
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| posted on 6/7/13 at 07:08 PM |
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I couldnt find a clear hose big enough 
Ben
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rdodger
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| posted on 6/7/13 at 07:13 PM |
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This any good?
http://www.ebay.co.uk/itm/Reinforced-CLEAR-PVC-Braided-Hose-Water-Pipe-Flexible-Plastic-Food-Air-Oil-Tube-/140697124967?pt=LH_DefaultDomain_3&var=
440131205000&hash=item20c233c067
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Ben_Copeland
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| posted on 6/7/13 at 07:25 PM |
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Thanks, i'll have a measure up and see what size i need.
Ben
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wylliezx9r
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| posted on 6/7/13 at 08:29 PM |
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Silly question maybe but iss the thermostat definately opening.Have u tried drilling a couple of holes in it ? That wworked for me when I was getting
flow problems due to trapped air.
HTH.
I spent a lot of money on booze, birds and fast cars. The rest I just squandered.
George Best
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Ben_Copeland
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| posted on 6/7/13 at 08:33 PM |
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quote:
Originally posted by wylliezx9r
Silly question maybe but iss the thermostat definately opening.Have u tried drilling a couple of holes in it ? That wworked for me when I was getting
flow problems due to trapped air.
HTH.
Yep, checked in boiling water and has holes drilled in it
Ben
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spaximus
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| posted on 6/7/13 at 09:21 PM |
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this is probably a silly suggestion, but have you got the belts correctly installed. I did once see a car where they guy had done away with the
tensioners, as it looked cool, but had then made the water pump run the wrong way.
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