40 replies to this topic

[OllieH]

About to re test....Just found another piece to the compression tester that had rolled underneath my tool box lid...whoops

Turns out adding the extension piece lowered the pressure down to 60/65

Edited by OllieH, 22 January 2016 - 02:41 PM.

[gazza82]

Could be valves .... if it's a leaded head and run on unleaded without additives it could have burnt the valve seats.

 

Had a 1098cc MG Midget that did same. Pull leads of plugs 3 AND 4 while idling .. continued, pull 1 or 2 and it would stop. Burnt out valves and that was in the days of Leaded fuel!! No compression on 3 and 4 ... bl**dy surprised I even managed to drive car to Krypton tuning place! (Who remembers them?!?)

Edited by gazza82, 22 January 2016 - 04:00 PM.

[Swift_General]

Compression test. Cylinder 4 - 75, Cylinder 3 - 75, Cylinder 2 - 0, Cylinder 1 - 0

Very noticeable air escaping noise when testing 2 and 1.

Never seen a reading of 0 before. Even 75 across the board would be too low (I'm assuming the the reading is 75 PSI and not 7.5 bar (circa 110 PSI). Also are you doing the test correctly, all plugs out with throttle wide open?). Either way with those results it looks like the head needs to come off for further investigation.

[OllieH]

Compression test. Cylinder 4 - 75, Cylinder 3 - 75, Cylinder 2 - 0, Cylinder 1 - 0

Very noticeable air escaping noise when testing 2 and 1.

Never seen a reading of 0 before. Even 75 across the board would be too low (I'm assuming the the reading is 75 PSI and not 7.5 bar (circa 110 PSI). Also are you doing the test correctly, all plugs out with throttle wide open?). Either way with those results it looks like the head needs to come off for further investigation.

Definitely tested correctly and yes 75 PSI. New gasket set ordered, head is coming off tuesday now. He'll have to sit there and look sad for a few days!

Could be valves .... if it's a leaded head and run on unleaded without additives it could have burnt the valve seats.
 
Had a 1098cc MG Midget that did same. Pull leads of plugs 3 AND 4 while idling .. continued, pull 1 or 2 and it would stop. Burnt out valves and that was in the days of Leaded fuel!! No compression on 3 and 4 ... bl**dy surprised I even managed to drive car to Krypton tuning place! (Who remembers them?!?)

This sounds exactly like my problem, however I do always add lead replacement to my fuel, not that it would rule out this problem.

[Cooperman]

You need to remove the heads, strip the valves out and check the valve seats (so you'll need a valve spring compressor), re-lap the valves in, assuming both valves and seats are in reasonable order, then fit a new head gasket.

Just clean back the surface of the head as it shouldn't need skimming unless it has been very seriously overheated.

Torque the head down accurately in the correct sequence and re-set the valve clearances to 0.012" (cold).

[gazza82]

 

 

Compression test. Cylinder 4 - 75, Cylinder 3 - 75, Cylinder 2 - 0, Cylinder 1 - 0

Very noticeable air escaping noise when testing 2 and 1.

Never seen a reading of 0 before. Even 75 across the board would be too low (I'm assuming the the reading is 75 PSI and not 7.5 bar (circa 110 PSI). Also are you doing the test correctly, all plugs out with throttle wide open?). Either way with those results it looks like the head needs to come off for further investigation.

Definitely tested correctly and yes 75 PSI. New gasket set ordered, head is coming off tuesday now. He'll have to sit there and look sad for a few days!

Could be valves .... if it's a leaded head and run on unleaded without additives it could have burnt the valve seats.
 
Had a 1098cc MG Midget that did same. Pull leads of plugs 3 AND 4 while idling .. continued, pull 1 or 2 and it would stop. Burnt out valves and that was in the days of Leaded fuel!! No compression on 3 and 4 ... bl**dy surprised I even managed to drive car to Krypton tuning place! (Who remembers them?!?)

This sounds exactly like my problem, however I do always add lead replacement to my fuel, not that it would rule out this problem.

 

 

But did the previous owner(s)?

[Steve220]

Personally I'd do an exchange head with new gasket set

[OllieH]

 

 

Compression test. Cylinder 4 - 75, Cylinder 3 - 75, Cylinder 2 - 0, Cylinder 1 - 0

Very noticeable air escaping noise when testing 2 and 1.

Never seen a reading of 0 before. Even 75 across the board would be too low (I'm assuming the the reading is 75 PSI and not 7.5 bar (circa 110 PSI). Also are you doing the test correctly, all plugs out with throttle wide open?). Either way with those results it looks like the head needs to come off for further investigation.

Definitely tested correctly and yes 75 PSI. New gasket set ordered, head is coming off tuesday now. He'll have to sit there and look sad for a few days!

Could be valves .... if it's a leaded head and run on unleaded without additives it could have burnt the valve seats.
 
Had a 1098cc MG Midget that did same. Pull leads of plugs 3 AND 4 while idling .. continued, pull 1 or 2 and it would stop. Burnt out valves and that was in the days of Leaded fuel!! No compression on 3 and 4 ... bl**dy surprised I even managed to drive car to Krypton tuning place! (Who remembers them?!?)

This sounds exactly like my problem, however I do always add lead replacement to my fuel, not that it would rule out this problem.
 

 
But did the previous owner(s)?

I know for sure the owner previous to me did, he stressed how important it was, I couldn't be certain about anybody before that.

[CityEPete]

Personally I'd do an exchange head with new gasket set

You know what,I agree. I'm running a leaded morris minor that is fine and I had a leaded mg bgt before that so I'm not one of these people that swaps heads for the sake of it, spending £200+ to save £10 a year is a waste imo but if the head has a problem as it certainly sounds like then I'd ditch it for a good unleaded one and a new gasket set, oil and filter, fan belt and water pump etc if its been a while, should be good for years once done.

[jakejakejake1]

Best bet is to whip the head off and have a look, if you have any luck it will just be the head gasket.

In which case it's a simple job, and won't cost much. But better to rule out the easy/ cheap options first before spending more cash on guessing.

[OllieH]

Best bet is to whip the head off and have a look, if you have any luck it will just be the head gasket.
In which case it's a simple job, and won't cost much. But better to rule out the easy/ cheap options first before spending more cash on guessing.

Fingers crossed it's just the head gasket, I drove it home less than half a mile after when the problem was really noticeable so I'm hoping it hasn't warped at all. It's coming off Tuesday and the. Going to look into getting a unleaded conversion in the next couple months.

[cal844]

Best bet is to whip the head off and have a look, if you have any luck it will just be the head gasket.
In which case it's a simple job, and won't cost much. But better to rule out the easy/ cheap options first before spending more cash on guessing.

Fingers crossed it's just the head gasket, I drove it home less than half a mile after when the problem was really noticeable so I'm hoping it hasn't warped at all. It's coming off Tuesday and the. Going to look into getting a unleaded conversion in the next couple months.

Personally do the unleaded conversion while its in bits

[Steve220]

 

 

Best bet is to whip the head off and have a look, if you have any luck it will just be the head gasket.
In which case it's a simple job, and won't cost much. But better to rule out the easy/ cheap options first before spending more cash on guessing.

Fingers crossed it's just the head gasket, I drove it home less than half a mile after when the problem was really noticeable so I'm hoping it hasn't warped at all. It's coming off Tuesday and the. Going to look into getting a unleaded conversion in the next couple months.

Personally do the unleaded conversion while its in bits

 

 

My thoughts exactly. Lots of places do exchange heads to upgrade to unleaded.

 

http://www.minispare...nts.aspx?100404

[jakejakejake1]

 

Best bet is to whip the head off and have a look, if you have any luck it will just be the head gasket.
In which case it's a simple job, and won't cost much. But better to rule out the easy/ cheap options first before spending more cash on guessing.

Fingers crossed it's just the head gasket, I drove it home less than half a mile after when the problem was really noticeable so I'm hoping it hasn't warped at all. It's coming off Tuesday and the. Going to look into getting a unleaded conversion in the next couple months.

 

 

I had unleaded inserts put in the exhaust valves and new guides all around for around £100, so as the other say, if you are considering getting it done it may be worth doing it while its in bits to save you the cost/ time of doing the head gasket (gasket set, oil etc) again soon. 
Also, I think you will be hard pressed to warp a head on a mini! The cast iron heads are fairly robust, you just need to make sure the head is level and there aren't any deep gouges/ burn marks etc. 

For peace of mind you could get it skimmed while having the inserts done if you aren't sure.

[CityEPete]

No point wasting money if you are planning on a head swap or upgrade anyway, I would want a new fan belt, oil and filter and fresh coolant along with a head gasket swap so that will need to be purchased twice and the labour will be double if you do not do the work yourself, I know it is more money right now but it is one of those times where you need to speculate to accumalate!