Martin R Posted June 5, 2013 Posted June 5, 2013 A bit of a PITA if you dont / cant DIY. Also an uneeded expense. it would only cost me the gaskets and the time and scrapped knuckles for the piece of mind. I think you are running out of options besides a head off look see unfortunatley.
chrislane Posted June 5, 2013 Author Posted June 5, 2013 I know you're all right - i need to get it sorted. But gav is still far from convinced it is the head. I need to get round to driving it a bit to see if i can spot any other issues. Otherwise i'll get to the end of the summer and not actually enjoyed it. Truth be told, i'm beginning to think i maybe should have sold it in the spring after all :-( that will all change though as soon as i get out in it again.
Martin R Posted June 5, 2013 Posted June 5, 2013 Hang on i have just remembered something. Brian ( Elise + imp ) made a post a while ago about a test for this. It involved a spark plug bored out and braised onto a bit of tube with an air line adapter on the other end. the idea being you pressurize the cylinder with compressed air. If you have a " blow " it will cause bubbles in the coolant. You can also use it to check for bent valves as well ( completely another subject ). I had one made and you are welcome to use it? PM Brian for the test procedure and i will pop it in the post HTH
chrislane Posted June 15, 2013 Author Posted June 15, 2013 Thanks martin. I'll send you my address by pm Brian - would be interested to hear how this is done. Thanks chris
jimbo07g41 Posted June 16, 2013 Posted June 16, 2013 Thats a leak down test. If you have a bent valve, (or Fire ring indent ), it wont seat proper and compressed air would escape.
Martin R Posted June 16, 2013 Posted June 16, 2013 Jamie, indeed it is. I presume you do each cylinder in turn. You would obviously need to have the valves closed on the cylinder being tested. In the case of a possible blow across the firering i suppose doing the test with the engine hot would help? Im not sure what pressure would be best to test at though? I will PM Brian to see if he has seen this thread. I will pop it in the post tomorrow Chris. I will also add a pic to this post for anyone else interested. Pics as promised. The first one is the complete thing. A bit of air pipe with a bored out spark plug one end and a male air fitting the other end. The spark plug body is soldered into the pipe. Also spark plug end. Air fitting end Fairly crude but effective
jimbo07g41 Posted June 16, 2013 Posted June 16, 2013 Hey Martin Hope your build is going well. My car is poppiing seals after trackdays at the minute, Thats cool and all you need. You just need it to be air tight into the head. All engines leak a bit. Ideally You need some gauges to measure the leakage. +30% and it needs work. I have read that you use 80 - 90 psi.
Martin R Posted June 16, 2013 Posted June 16, 2013 Jamie, hopefully the car will be progressing shorlty. Thats about 6 bar then? My compressor has a guage on it. For a blow test, it may well be just a case of pressurising the cylinder with the valves closed and look for bubbles in the coolant?
jimbo07g41 Posted June 16, 2013 Posted June 16, 2013 I have no practical experience of this but that is the theory. I have only done it with a head off the block and petrol, so you can see the valves closed.
Elise+Imp Posted June 16, 2013 Posted June 16, 2013 Hi gents, i've not really been following the thread, but chris did send me a message, my reply is below: .......... basically you fill the cylinder with compressed air, so it needs to be at TDC or it will turn the crank, normally you are listening for noise to indicate a combustion leak such as leaking valves, which give noise in the inlet or exhaust, poor piston rings give noise in the crankcase audible from oil filler cap. A proper leakdowm tester hads reference gauges so you can quantify the % loss, you may find some info elsewhere on the net about them. In your case I would pressurise each cylinder in turn with as much pressure as your compressor will give, at least 90psi. Then I would listen to the header tank for air, you may not get anything, so fit the cap and watch to see if the level changes, it may go up / down indicating pressurisation of the water or hopefully the level will stay the same. leave it pressurised for at least 5 mins then release the cap, see if it hisses much, if so then it is leaking air from a cylinder. Do every cylinder one by one and see what happens, I would do it cold initially, then run the car to temp, let it cool for around 10 mins and try again, you don't need to run it between testing different cylinders. but it might be something that changes once warm. ........... Brian
Martin R Posted June 16, 2013 Posted June 16, 2013 Brian, thanks for that Chris, let us know what happens please?
chrislane Posted June 17, 2013 Author Posted June 17, 2013 Martin / Brian - thanks both for this. If there is anyone going to the fish meet tomorrow who can use Brians description above and point at bits of the car to say "do this" and "do that" it would be much appreciated!!!!!! I'm sure it is simple (and i'm sure Brian has dumbed it down for me!) but i could still do with a bit of old fashioned pointing! Cheers Chris oh, and has anyone got an air compressor i could borrow please???? ;-) Edit to ask what is quite probably a numpty question: what is "TDC" in first line of Brians description? A bit of googling and i've answered my own question "Top Dead Centre" - i might need someone to talk me through how to do this right though!
Martin R Posted June 17, 2013 Posted June 17, 2013 Might be worth a phone call to Gav and ask him to do it for a few beer tokens. Im sure he will have a compressor. It is in the post BTW.
chrislane Posted June 17, 2013 Author Posted June 17, 2013 Ye of little faith martin, ye of little faith ;-)
russelld Posted June 17, 2013 Posted June 17, 2013 Chris, I will try to make the meeting tomorrow and will bring my finger !!!
Recommended Posts
Archived
This topic is now archived and is closed to further replies.