Author Topic: Head gasket leak  (Read 1159 times)

Offline hdawson

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Head gasket leak
« on: 09.10. 2016 10:38 »
Hi all.
The A10 is running great at the moment but has a slight  leak from the head. Nothing major and I am  reluctant to do anything as the riding season is upon us in South Aus (yes- apologies to both our northern hemisphere mates and my aussie  "all weather heroes")
Because every time I delve into the guts it opens a pandora's box of more issues, what should I expect in regards to replacing parts.
I would like to avoid having the beast apart and having to order/wait on parts for weeks.
So considering the "worst case scenario", what would be your recommendations.
Let's pretend money is not an issue.
Sorry if this question is a bit simple but any advise would be greatly appreciated.
Cheers , Hadrian.


61 BSA Super Rocket (cafe).
51 Matchless G9 Clubman.
81 Suzuki GSX 750 ES.
02 Triumph Sprint.

Online BSA_54A10

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Re: Head gasket leak
« Reply #1 on: 09.10. 2016 10:54 »
You have 2 weeks between now & the BSA National at Beaudesert Qld  which means this week you are going to pull the head off, anneal the gasket and replace it so you can do some test rides next weekend.
Only thing you can do to save time is buy a spare gasket and anneal it before hand.
Most like to slap a little copper slip on both sides before fitting.

OTOH you can try backing off the head bolts 1/4 turn then retensioning them in 2 steps, some times the head settles a little, just enough to weep, but it will get worse.
Bike Beesa
Trevor

Offline morris

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Re: Head gasket leak
« Reply #2 on: 09.10. 2016 13:28 »
... or if money is not an issue, have someone else to do it for you  *smile* ;)
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Re: Head gasket leak
« Reply #3 on: 09.10. 2016 20:14 »
G'day Hadrian.
I agree with Trevor. Re-tension will help for now but not very long. Are you sure it's the head gasket and not the rockerbox leaking? Either way the box has to come off so may as well lift the head too. Are the proper washers fitted under the bolt heads? Normal mild steel washers can cup and you loose bolt tension.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
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Offline East_Coast_BSA

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Re: Head gasket leak
« Reply #4 on: 09.10. 2016 23:51 »
When I first got my engine back from the builder, he gave me specific instructions on break in.  I ran the bike at 2000 rpm for two minutes (with a box fan in front) and shut it off for four minutes.  I kept repeating the process until the engine was warmed up.  The next day I re-torqued the head and repeated the warm up process.  It took four head retorques before everything stayed tight.  At 1500 miles, the head gasket started leaking.  What I was never told about was the "Follow-up" torque checks.  I annealed the old head gasket and gave it a light spray of Permatex Copper.  I went through the same initial torque process and it took four cycles to get everything tight (again).  After that I checked the torque again at 25, 125, 250, 500 and 1000 miles.  They were tight at 1000, but the earlier four checks, there were still loose bolts (usually in the inner section).  I've checked the torque at 2000 and 3000 miles and everything has been good.  I don't know if they are supposed to require this much "Baby-sitting", but that's the route I ended up taking.

Online KiwiGF

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Re: Head gasket leak
« Reply #5 on: 10.10. 2016 02:18 »
Your unlucky or something is not quite right, last time I did after I blew a head gasket (due my torque wrench over reading by a third) I checked mine at 1000 miles and none needed tightening. This is with an iron head with solid copper gasket freshly annealed, not greased or goo'd and with hardened washers under the bolts (home made thick ones). It seems a bit of a faff to check them several times?

To check the head bolts are tight I simply used the torque wrench at the same setting and looked to see if they moved or not, I do not back them off then re tighten, is that how you are doing it?
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Offline Rocket Racer

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Re: Head gasket leak
« Reply #6 on: 10.10. 2016 05:25 »
Its got to be done , the difference between a weep and blown is not something you want to deal with mid journey  *eek*.
And when you mention to your riding colleagues you had plenty of time before the run to sort it but didn't  *problem*, you'll certainly wish you did it when you had the chance

Attached are cake streets classics recommendation for assembly.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline East_Coast_BSA

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Re: Head gasket leak
« Reply #7 on: 10.10. 2016 07:22 »
I have an Aluminum head.  I don't back them off, I just double-check the torque.  It's usually only one or two bolts that are loose, not the entire bunch.  It's not always the same bolts, but it tends to be the bolts closer to the center of the head.

Offline TT John

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Re: Head gasket leak
« Reply #8 on: 10.10. 2016 08:26 »
Hi all.
The A10 is running great at the moment but has a slight  leak from the head. Nothing major and I am  reluctant to do anything as the riding season is upon us in South Aus (yes- apologies to both our northern hemisphere mates and my aussie  "all weather heroes")
Because every time I delve into the guts it opens a pandora's box of more issues, what should I expect in regards to replacing parts.
I would like to avoid having the beast apart and having to order/wait on parts for weeks.
So considering the "worst case scenario", what would be your recommendations.
Let's pretend money is not an issue.
Sorry if this question is a bit simple but any advise would be greatly appreciated.
Cheers , Hadrian.

Hadrian.

I had the same problem and was getting to the point of distraction, when I noticed that it was coming from the oil feed unions on the rocker box, after retightening these I still had oil coming from somewhere, always looked like the head but I was not convinced so I removed the rocker box and replaced the gaskets on it with a solid copper set I had made, problem solved, no leaks at all now.
Since solving this problem, I had several sets of solid soft copper, lazer cut for A7/ A10 rocker boxes and I am now offering them for sale at £16 - 00 per set plus p+p.

Kind regards TTJohn

Offline hdawson

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Re: Head gasket leak
« Reply #9 on: 10.10. 2016 09:01 »
... or if money is not an issue, have someone else to do it for you  *smile* ;)
Not quite what I meant as I want to do as much as I can, as that's the fun part.
I just thought that I should have new valves or springs or etc on hand or expect to re grind, or other issues that the more experienced members could warn me to expect.
I've had the rocker box off many times(even used permatex blue once - that was a mistake as it was a nightmare to remove)
Oil feed to the rocker box banjos seems to be tight(after much tweaking)
KiwiGF-exactly my concern!
Muskrat-what are 'proper washers'?
BSA54A10-Love to be there but my knees couldn't take it. Maybe a trailer??
And thanks to all as usual

61 BSA Super Rocket (cafe).
51 Matchless G9 Clubman.
81 Suzuki GSX 750 ES.
02 Triumph Sprint.

Offline hdawson

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Re: Head gasket leak
« Reply #10 on: 10.10. 2016 09:04 »
Thanks TTjohn.
I'll check that also.
Cheers.

61 BSA Super Rocket (cafe).
51 Matchless G9 Clubman.
81 Suzuki GSX 750 ES.
02 Triumph Sprint.

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Re: Head gasket leak
« Reply #11 on: 10.10. 2016 09:40 »
G'day Hadrian.
The proper ones https://www.draganfly.co.uk/index.php/accessories-a-misc/product/4025-
Any decent auto parts supplier/engine reconditioner (repco, autopro etc) should have 3/8" head bolt washers. Their thicker and harder than normal washers.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online Greybeard

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Re: Head gasket leak
« Reply #12 on: 10.10. 2016 09:44 »
G'day Hadrian.
The proper ones https://www.draganfly.co.uk/index.php/accessories-a-misc/product/4025-
Any decent auto parts supplier/engine reconditioner (repco, autopro etc) should have 3/8" head bolt washers. Their thicker and harder than normal washers.
Cheers
I couldn't find any head bolt washers when I wanted some so I got a  friend to turn some thick washers up from tough steel
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