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- Thread starter Hooper11772
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Gray_Cat
Jedi Warrior
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Roger:
I read about another Spridget owner (in another site) having the same issue. Long story short, it turned out to be the head. The duff head had been thoroughly reworked prior to installation but had a serious defect after all.
Was the head on your car magnafluxed to check for cracks? Even so, it's unpredictable when a part may go toxic. Let us know what the leak down test results are - being patient and methodical will pay you huge dividends!
Roy
I read about another Spridget owner (in another site) having the same issue. Long story short, it turned out to be the head. The duff head had been thoroughly reworked prior to installation but had a serious defect after all.
Was the head on your car magnafluxed to check for cracks? Even so, it's unpredictable when a part may go toxic. Let us know what the leak down test results are - being patient and methodical will pay you huge dividends!
Roy
OP
Hooper11772
Senior Member
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Update: I was able to purchase a leakdown tester from my local HF store. It was actually less then expected $29.99. I haven't had a chance to use it yet but i'm going to try to get to the garage this evening. Is there anyone thats used one of these that has some advice on how to perform testing? The manual that came with it doesnt have too much to go by and this is all new to me!
jvandyke
Luke Skywalker
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I haven't done it yet but I stopped at HF a few minutes ago, they had the advance timing gun I want (I broke mine and it wasn't the advance type) but they didn't have the leak down tester. What did you end up paying? I think the process is pretty similar to compression test I believe, pull all plugs, set a cylinder to TDC (so valves are closed), car in neutral (so it doesn't turn over on you I guess) put in 100psi and see how far it drops and holds, if you hear a hiss from the exhaust you have a leaky exhaust valve, if you hear a hiss from the intake side, bad intake valve, if you hear something in the crankcase venting somewhere: rings.
SilentUnicorn
Yoda
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Easy to do. Start with number one cylinder. remove all plugs, REMOVE COIL LEAD, bring the piston up to TDC with both number one cylinder valves closed. Use something to indicate the piston position( i use a small screwdriver) for number one piston it should be near the TDC mark on the crank pulley. Screw in the gauge- apply 100 pounds of air to the cylinder using the first gauge. read your Leak down on the second gauge. WHEN APPLYING AIR KEEP HANDS AND FEET AWAY FROM THE ENGINE ! If you are not exactly on TDC the pressure can cause the piston to go to BDC rapidly spinning the fan and hurting you. IF you have 100#s of air at gauge one and your second gauge reads 90#s then you have 10% leak down. If you cant hold 100 pounds you may use lower pressure. There is a chart HERE for lower pressures. Listening at the tailpipe, the intake or the dipstick will tell you where the leak is. Also look for bubbles in the coolant or a change of level when you apply the air.
Repeat for pistons 2,3,4
reading the results
"Five to 10 percent loss indicates an engine in great to good running order. An engine between 10 and 20 percent can still run okay, but it’ll be time to keep an eye (or ear) on things. Above 20 percent loss and it may be time for a teardown and rebuild. Thirty percent? Major problems. The percent of leakage should also be consistent across the cylinders. Any great differences indicate a problem in that cylinder."
also look here
https://www.mobiloil.com/USA-English/MotorOil/Car_Care/DIY/Engine_Leakdown_Test.aspx?pg=2
mark
Repeat for pistons 2,3,4
reading the results
"Five to 10 percent loss indicates an engine in great to good running order. An engine between 10 and 20 percent can still run okay, but it’ll be time to keep an eye (or ear) on things. Above 20 percent loss and it may be time for a teardown and rebuild. Thirty percent? Major problems. The percent of leakage should also be consistent across the cylinders. Any great differences indicate a problem in that cylinder."
also look here
https://www.mobiloil.com/USA-English/MotorOil/Car_Care/DIY/Engine_Leakdown_Test.aspx?pg=2
mark
Gray_Cat
Jedi Warrior
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Roger:
Maybe this has been mentioned in the thread so am sorry if this is repetitious;
have you retorqued the cylinder head since you have fired up the engine? If not, do so when the engine is cold before you do anything else. I don't have the torque specs handy but should be posted in the Moss on line catalog or maybe someone can just insert them here for you.
Retighten the nuts to torque specs starting in the center and work your way out to the edge of the head.
Roy
Maybe this has been mentioned in the thread so am sorry if this is repetitious;
have you retorqued the cylinder head since you have fired up the engine? If not, do so when the engine is cold before you do anything else. I don't have the torque specs handy but should be posted in the Moss on line catalog or maybe someone can just insert them here for you.
Retighten the nuts to torque specs starting in the center and work your way out to the edge of the head.
Roy
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Hooper11772
Senior Member
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Thats a great link and really good instructions. I'll run through it tonight and let you guys know what I find. I'm hoping for anything but cracked block or rings! I do not want to pull this engine again! Thanks or all the help.
OP
Hooper11772
Senior Member
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Good call Roy, I have not done this since the rebuild. I currently don't have a torque wrench but have been meaning to pick one up. Chris and I torqued them originally but I have read they loosen up after the engine warms and cools a few times! Do you think that would cause this? That seems like it would be way too easy!
SilentUnicorn
Yoda
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Gray_Cat said:
Good point!
mark
OP
Hooper11772
Senior Member
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Update:
Well, I torqued the head down last night it was pretty loose probably a half to full turn on all studs. I followed the instructions listed in the Haynes manual for sequence. Started her up and the smoke was still there. I let it run for a bit to see if it was just residual but was still smoking after about 10 minutes and when I got on it at idle it really smoked.
I performed the leakdown test as well last night although I had a difficult time getting the tester to work correctly. I think it may be defective. The issue I was having is when I opened the valve to charge the cylinder with air I could only get to around 40 PSI before the percentage gauge was set at 0. As a result it was difficult to hear any leaks since the pressure wasn't all that great. Also the percentage didn't seem accurate since I could hear air but the percentage was minimal ( less than 5%).
However despite these setbacks I still was able to hear where leaks were occurring I just don't have a percentage. For cylinder #1 I had a slight exhaust hiss from the tail pipe. #2 had a hiss from the intake valve that I could hear through the damper in the front SU. #3 was the worst with a pretty good hiss from the intake valve as well, and #4 had a tailpipe hiss as well as a very small gurgle from the dip stick tube.
#4 concerned me the most since there was obviously some blow by in that cylinder but the rest seem to be isolated to valve seating issues. I was definitely at TDC on all cylinders tested so the valves should have been closed completely and it was evident that they were not.
My next question is I definitely need the head re worked but what should I do for this? I was planning on pulling the head and testing each of the exhaust valve/intake valve per cylinder to look for leaks. I saw a university motors video where this was done using gas. I was looking at prices and was thinking i'll replace all valves exhaust and intake as well as springs and intake rubber. I was also thinking new guides but was unsure how much would it would cost to get those installed via a machine shop and should I get the seats done as well or just lap the new valves upon install? I had the head hot tanked a year ago so I was hoping if the surface looks good I can do most of this myself. Any advice from someone who has had this done? Is it possible to install the guides myself?
Well, I torqued the head down last night it was pretty loose probably a half to full turn on all studs. I followed the instructions listed in the Haynes manual for sequence. Started her up and the smoke was still there. I let it run for a bit to see if it was just residual but was still smoking after about 10 minutes and when I got on it at idle it really smoked.
I performed the leakdown test as well last night although I had a difficult time getting the tester to work correctly. I think it may be defective. The issue I was having is when I opened the valve to charge the cylinder with air I could only get to around 40 PSI before the percentage gauge was set at 0. As a result it was difficult to hear any leaks since the pressure wasn't all that great. Also the percentage didn't seem accurate since I could hear air but the percentage was minimal ( less than 5%).
However despite these setbacks I still was able to hear where leaks were occurring I just don't have a percentage. For cylinder #1 I had a slight exhaust hiss from the tail pipe. #2 had a hiss from the intake valve that I could hear through the damper in the front SU. #3 was the worst with a pretty good hiss from the intake valve as well, and #4 had a tailpipe hiss as well as a very small gurgle from the dip stick tube.
#4 concerned me the most since there was obviously some blow by in that cylinder but the rest seem to be isolated to valve seating issues. I was definitely at TDC on all cylinders tested so the valves should have been closed completely and it was evident that they were not.
My next question is I definitely need the head re worked but what should I do for this? I was planning on pulling the head and testing each of the exhaust valve/intake valve per cylinder to look for leaks. I saw a university motors video where this was done using gas. I was looking at prices and was thinking i'll replace all valves exhaust and intake as well as springs and intake rubber. I was also thinking new guides but was unsure how much would it would cost to get those installed via a machine shop and should I get the seats done as well or just lap the new valves upon install? I had the head hot tanked a year ago so I was hoping if the surface looks good I can do most of this myself. Any advice from someone who has had this done? Is it possible to install the guides myself?
jlaird
Great Pumpkin
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Ok you have proved the point. Remove the head and take it to a machine shop for a rebuild. Cleaning, leveling, new freeze plugs, guides, and grinding of the valves.
Might just as well have it done right. However, your valves prop do not need replaced just reworked.
Take it in and get a price.
Might just as well have it done right. However, your valves prop do not need replaced just reworked.
Take it in and get a price.
SilentUnicorn
Yoda
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Hooper,
are you saying that you have 100#s of air from your source, but could only get to 40#s of air in a cylinder? -not good. Since you are sure that you were TDC- then as you say, the head needs work. The Oil in the cylinders concerns me, but since it sounds like you will be pulling the head you can inspect the cylinder bores at that time.
I just had new guides and seats cut at a local shop and the cost was less than 150$. I would recommend that you do new guides. Yes you can remove and install the new ones your self if you have a press. All that is needed is a two diameter drift to press the old out and the new in. the installed height should be in the manual. that may save you a couple of dollars if you can do this yourself. from the sounds of those numbers i would certainly get the seats re-cut, and in order to do that the shop may want the guides and valves to properly locate the seats when they cut them.
m
are you saying that you have 100#s of air from your source, but could only get to 40#s of air in a cylinder? -not good. Since you are sure that you were TDC- then as you say, the head needs work. The Oil in the cylinders concerns me, but since it sounds like you will be pulling the head you can inspect the cylinder bores at that time.
I just had new guides and seats cut at a local shop and the cost was less than 150$. I would recommend that you do new guides. Yes you can remove and install the new ones your self if you have a press. All that is needed is a two diameter drift to press the old out and the new in. the installed height should be in the manual. that may save you a couple of dollars if you can do this yourself. from the sounds of those numbers i would certainly get the seats re-cut, and in order to do that the shop may want the guides and valves to properly locate the seats when they cut them.
m
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Hooper11772
Senior Member
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Hi Silent Unicorn,
I did have 100#s of air from my compressor but if I raised the PSI to the cylinder closer to the 100 mark the percentage gauge would pass 0% and go into the negative. So instead I just gave the cylinder air unil the percentage read zero for the needle. This was on average about 40 PSI of pressure.
When you dropped off your head to the shop did you provide the guides and valve seats or is that something that they ordered? I'll have them do the guides and seats and then install the valves, springs and rockers myself. If I need to rder do I have to take measurements or anything or is there only one valve seat and guide for a 1275 head? I need to find a good machine shop now. Does anyone know of one in the mass area? Sorry for all the questions and thanks for all the help!
I did have 100#s of air from my compressor but if I raised the PSI to the cylinder closer to the 100 mark the percentage gauge would pass 0% and go into the negative. So instead I just gave the cylinder air unil the percentage read zero for the needle. This was on average about 40 PSI of pressure.
When you dropped off your head to the shop did you provide the guides and valve seats or is that something that they ordered? I'll have them do the guides and seats and then install the valves, springs and rockers myself. If I need to rder do I have to take measurements or anything or is there only one valve seat and guide for a 1275 head? I need to find a good machine shop now. Does anyone know of one in the mass area? Sorry for all the questions and thanks for all the help!
SilentUnicorn
Yoda
Offline
pass zero and go negative??
not to question your ability,(please dont take offense) but you did hook it up correctly? Air from comp. into regulator on the left side of tester- other side to the piston? the quick discon. is for the spark plug side. Iam trying to figure out how you could pull a vaccum on the gage the way you describe.
yes -i provided all the parts. guides and valves i did the springs and the rest myself.
i would give THESE fellows a call for your parts, very nise and knowledgeable to deal with. NFI
mark
I am working with a fella (neighbor) right now on doing his 1275 head. He burnt a hole right thru a valve.
not to question your ability,(please dont take offense) but you did hook it up correctly? Air from comp. into regulator on the left side of tester- other side to the piston? the quick discon. is for the spark plug side. Iam trying to figure out how you could pull a vaccum on the gage the way you describe.
yes -i provided all the parts. guides and valves i did the springs and the rest myself.
i would give THESE fellows a call for your parts, very nise and knowledgeable to deal with. NFI
mark
I am working with a fella (neighbor) right now on doing his 1275 head. He burnt a hole right thru a valve.
OP
Hooper11772
Senior Member
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No offense taken, This is all new to me but what I meant was when I opened the valve you see on the actual unit to let air flow into the cylinder the percentage drops from 100% to 0% as it should but then it keeps going past the zero and pins against the pin.
At this point it's at 40 PSI on the left guage and if I increase to 100 PSI on the left guage the percentage never moves in the positive direction.
I'll give those guys a call and see if I can grab those and parts and go from there. Thanks for all the help everyone I definitely wouldn't have gotten to this point without all of you!
At this point it's at 40 PSI on the left guage and if I increase to 100 PSI on the left guage the percentage never moves in the positive direction.
I'll give those guys a call and see if I can grab those and parts and go from there. Thanks for all the help everyone I definitely wouldn't have gotten to this point without all of you!
SilentUnicorn
Yoda
Offline
hmmm something sounds fishy with that gauge. normally when air is applied both gauges should move CW. Left gauge to 100 and right gauge to 100 (if leakdown is zero) if right gauge only goes to 90 then leakdown is 10%.
keep us posted
mark
keep us posted
mark