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| Curtis |
Posted: 2006/11/20 14:55 Updated: 2006/11/20 14:55 |
Home away from home   Joined: 2006/7/24 From: Sydney Posts: 553 |
 Re: head gasket "sweating" may as well change head gasket ur halfway there already and no matter wat u do its still only going to get slowly worse there cheap as chips too.
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| ddgonzal |
Posted: 2006/11/20 15:14 Updated: 2006/11/20 15:14 |
Moderator   Joined: 2001/5/3 From: 48 North Posts: 31575 |
Re: head gasket "sweating" Curtis, what do you mean "it will get worse"? I don't think so. Also, retorquing the head bolts is not "halfway" to replacing the gasket, only the rocker cover is removed.
GXman, when re-torquing bolts, yes you are supposed to loosen it, before re-torquing. Not because it is "corroded", but because that's how it is done.
Do you have the factory service manual for the 1200? It outlines the procedure in detail.
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| 1200GXman |
Posted: 2006/11/20 15:21 Updated: 2006/11/20 15:21 |
No life (a.k.a. DattoMaster)   Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" DD
Yes, I have the manual. I unfortunately forgot to check and just torqued.
If it is required to loosen and retorque, then I might aswell remove them completely and fit the number 13 bolts and torque them with the higher settings.
Just another quick question. If I fit the number 13 bolts and torque them. Will it be a good idea to drive the car 1000km and just to be save retorque them again?
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| Dodgeman |
Posted: 2006/11/20 15:25 Updated: 2006/11/20 15:25 |
No life (a.k.a. DattoMaster)  Joined: 2003/6/27 From: Southern Tablelands N.S.W. Australia Posts: 8287 |
Re: head gasket "sweating" Loosening the headbolt allows you to overcome the 'stiction' that occurs when the bolt is tight. It takes additional torque to get it moving.
Just loosen it a little, & if you like, take it out & place a little oil on the threads & under the head. Don't use grease.
When you tighten it up again, the resistance to turning is less & the correct figure will be more easily & accurately obtained.
The '13' marked bolts were used on the a14 engines, so surely a set would be economicly obtained through a wreckers somewhere, & if not, then check the price for new ones. They just might be affordable.
Ddgonzal is right. Many a headgasket has been saved by a timely retensioning of the head, & as for a retension being halfway to replacing the gasket, .... ummmm, .. no.
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| 1200GXman |
Posted: 2006/11/20 17:05 Updated: 2006/11/20 17:05 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" This is why I have decided that I am going to work on my cars myself in the future.
I really don't know what the mechanic did.
I don't know what torque setting he used for the head bolts, so I am a bit in the dark now. I will remove tappet cover again this weekend and loosen them with half a turn and torque them down again. Maybe a little higher setting. I just don't like the idea of retightening used head bolts. I was always under the impression that used head bolts must be thrown away.
Just out of curiosity I will retighten and see what happens. If it still does'nt work and "sweats" I will remove head and do a proper job myself.
Thanks for all the replies.
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| Dodgeman |
Posted: 2006/11/20 17:19 Updated: 2006/11/20 17:19 |
No life (a.k.a. DattoMaster) Joined: 2003/6/27 From: Southern Tablelands N.S.W. Australia Posts: 8287 |
Re: head gasket "sweating" Aparently some newer engines require head bolt replacement when they are removed, but I have always worked with older stuff & have never used a new head bolt yet. I have never had a bolt failure or suffered a problem as a result of head bolt problems. Just stay within the recomended settings & you will be fine. Use the settings for regular bolts untill you can source a set of replacements.
From all the problems we have been reading about regarding professional automotive workshops in South Africa, I makes me wonder if there are any real mechanics there at all. Hopefully we are only reading about the tiny minority who really amount to little more than oxygen thieves.
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| ddgonzal |
Posted: 2006/11/20 17:33 Updated: 2006/11/20 17:33 |
Moderator Joined: 2001/5/3 From: 48 North Posts: 31575 |
Re: head gasket "sweating" Quote: I just don't like the idea of retightening used head bolts. Nissan recommends re-using the head bolts. As Dman alluded to, it's only newer engine designs where you have to throw away the head bolts and buy new ones when changing the gasket. Those use a "stretch" bolt designed for high clamping forces and more accurate torquing. But that doesn't apply to the A-series engines. |
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| kululadotgroen |
Posted: 2006/11/20 17:42 Updated: 2006/11/20 17:42 |
No life (a.k.a. DattoMaster)  Joined: 2006/7/12 From: Cape Town ZA Posts: 1054 |
Re: head gasket "sweating" Quote: From all the problems we have been reading about regarding professional automotive workshops in South Africa, I makes me wonder if there are any real mechanics there at all. Hopefully we are only reading about the tiny minority who really amount to little more than oxygen thieves. Unfortunately this is the case, there are very few reputable automotive workshops, more so after market ones, and a vast majority that I wouldn't even take my lawnmower to. This is the reason why I start servicing any car I drive myself, the moment that it's out of warranty, you can't even trust most of the carmaker's services. I've only ever owned Ford, VW, Datsun and some Korean thing that never seems to break. The Datsun's and Fords having non stretch bolts, and the VW stretch bolts. I sometimes had nightmares after assembling a VW engine, having to torque it to some NM's and then a bunch of degrees...  |
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| kululadotgroen |
Posted: 2006/11/20 17:31 Updated: 2006/11/20 17:31 |
No life (a.k.a. DattoMaster) Joined: 2006/7/12 From: Cape Town ZA Posts: 1054 |
Re: head gasket "sweating" Quote: Loosening the headbolt allows you to overcome the 'stiction' that occurs when the bolt is tight. It takes additional torque to get it moving. As per our private email conversation...  We normally undid the bolts about a quarter turn , and then re-torqued. Without exception they turned at least a quarter turn, sometime more further than if you just torqued. Also watch out to put to much oil in the bolt hole, or to drip to much in there when putting the bolt in. I've seen a block cracked open by the hydraulic pressure caused when tightening the bolts. We squirted some oil on the threads, under the washers and under the bolt heads, of all the bolts and let them lie on a piece of carton, then started inserting the first bolt. The little oil left after most have run of, is more than enough for lubrication. A series head bolts are still the ones that tighten the head by "brute force" they are not designed to stretch, and if you do tighten them to the point where they stretch, they will be weakened, and probably break when you least want them to. We re-used them after an overhaul, the car's were mostly sold before they ever needed an overhaul again...  Newer cars like your VW use the "stretch" bolts, and even though I know about people who use them twice, you should replace them after every use. I certainly replace them every time, a s they go for R98 a pop... |
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| ddgonzal |
Posted: 2006/11/7 1:02 Updated: 2006/11/7 1:02 |
Moderator Joined: 2001/5/3 From: 48 North Posts: 31575 |
Re: head gasket "sweating" This is normal. It is seeping at the oil gallery, not around the combustion chamber, so it will not "weaken" the gasket. Yes, the head bolts should *always* be torqued with a torque wrench. Never guess. It won't warp the head. Just borrow a torque wrench and re-torque them. The A12GX engine uses the same torque as the regular A12 engine. The "12" bolts are the early engine. See the torque figures here: Tune-Up Information |
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| 1200GXman |
Posted: 2006/11/6 21:57 Updated: 2006/11/6 21:57 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" Help please!!
I noticed that my head gasket is "sweating" on the distributor side of the engine.
Here is the pic I took of it.
It is only at cylinder 1 and 2 if you are standing in front of the engine and cylinder 1 is at the front.Only the distributor side.The rest is dry.
I think I must retorque the cylinder head to see if it is not a bit loose.
My questions:
1. The oil has now "sweated" through the head gasket. Will this not weaken the head gasket at this location?
2. If the bolts are a bit loose here with comparison of the others, would my cylinder head not have warped due to cold, warm, cold, warm conditions of usage? If so, If I retorque, will it basically straigten again through use again?
ANY info appreciated.
The head bolts are stamped with a number 12 on them. What is the torque specs of a A12GX engine in Nm please.
I have checked the radiator water and also inside the tappet cover. Everything looks like it should.
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| killer1200 |
Posted: 2006/11/7 1:06 Updated: 2006/11/7 1:06 |
No life (a.k.a. DattoMaster)  Joined: 2004/5/28 From: Adelaide, South Australia Posts: 1817 |
Re: head gasket "sweating" Quote: 1. The oil has now "sweated" through the head gasket. Will this not weaken the head gasket at this location? If it's been doing it for a while it could have, but at any rate the outcome will be the same you just have to change the head gasket agian. Quote: 2. If the bolts are a bit loose here with comparison of the others, would my cylinder head not have warped due to cold, warm, cold, warm conditions of usage? If so, If I retorque, will it basically straigten again through use again? I would take all the bolts out make sure they are clean and then retorque them not just the ones near where the problem is. Someone is sure to know the torque. Good Luck. |
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| 1200GXman |
Posted: 2006/11/7 13:13 Updated: 2006/11/7 13:13 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" Well, now I'm sitting with a problem. One is saying not to worry and the other is saying it might weaken the head gasket. What to do. I have a torque wrench at home.No problem there. I was at the other mechanic friend who was working for the Datsun racing team in the late 70's early 80's. He suggested, and I think I will do this and then see what happens, is to retorque the head bolts and see if they ARE loose or not. If they are loose, the torque wrench will click after some movement while if they are correctly torqued it will click without any extra tightning. This I will do with all the head bolts not only these ones at the front. I am mostly worried that the head got warped if they are loose, but logic tells me that if I torque it tight again the heat and cold process through usage will pull it straight again. Any other suggestions? ddgonzal I checked the Haynes manual I have for the A12 Datsun. In there they say the head must be torqued 40 -> 43 lb/ft. The link you gave me says 33 -> 36 lb/ft. What would be recommended. |
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| killer1200 |
Posted: 2006/11/7 14:58 Updated: 2006/11/7 14:58 |
No life (a.k.a. DattoMaster) Joined: 2004/5/28 From: Adelaide, South Australia Posts: 1817 |
Re: head gasket "sweating" Quote: One is saying not to worry and the other is saying it might weaken the head gasket Forget i said it. Go with your plan. |
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| Mildman |
Posted: 2006/11/7 15:02 Updated: 2006/11/7 15:02 |
No life (a.k.a. DattoMaster)  Joined: 2003/9/2 From: SE Melbourne Posts: 3195 |
Re: head gasket "sweating" Quote:
1200GXman Date: 2006/11/7 23:13:44
I checked the Haynes manual I have for the A12 Datsun. In there they say the head must be torqued 40 -> 43 lb/ft. The link you gave me says 33 -> 36 lb/ft.
What would be recommended. The Gregorys manual says 45ft/lb - so I'd go with between 40-45 ft/lb. Head bolts do loosen with heating, cooling and time and could be your cause...at least it is the first cause to eliminate anyway. |
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| 1200GXman |
Posted: 2006/11/7 15:09 Updated: 2006/11/7 15:09 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" Quote: killer1200 Sorry man, did'nt mean to offend you.  I just wanted to know how serious it is. you gave me the idea it is serious and ddgonzal gave me the idea it is a common thing that happens to them. I just dont want to pull the cylinder head off unless it is really required. all know me as the worrier on this club. It is a GX cylinder head and I don't want to mess it up. Also don't want to drive on the freeway with a headgasket blowing unexpectedly. South Africa is not one of the savest places to pull of the road with a broken engine. |
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| ddgonzal |
Posted: 2006/11/7 16:42 Updated: 2006/11/7 16:42 |
Moderator Joined: 2001/5/3 From: 48 North Posts: 31575 |
Re: head gasket "sweating" The sweating is normal -- most A series engines have it. They go decades like this. A series aluminum heads rarely warp. They move around a bit, and are apt to "blow" the gasket if not correctly tightened (or if they get too hot), but in almost all cases they are not warped even so. Most mechanic shops says "mill the head flat" but the reality is that they don't even bother to check them against factory specifications. GX man, don't worry so much. Just retorque the head bolts, and be proud of the weeping gasket, it is the mark of Nissan. The early head bolts (1971 to 1972-1/2) are not strong enough for the high torque of the later A12 bolts. What is much more important is getting an equal torque on each bolt. Tighten them in the Nissan recommended pattern. Did you read the Tune Up article?Quote: A12 (to engine number A12-470084) 33-36 ft lb (4.5-5.0 mkg)
A12 (newer) 40-43 ft lb (5.5-6.0 mkg) By the way, what kind of gasket is it? |
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| 1200GXman |
Posted: 2006/11/7 17:29 Updated: 2006/11/7 17:29 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" Thanks ddgonzal
I am going to torque the head bolts then to the specs on this website (33 -> 36 lb/ft) and see what the torque wrench tells me(click before any movement of the bolt or click after movement of the bolt).
Because my head bolts have the 12 stamped on them, I don't want to overtighten them and sit with a broken head bolt.
Thanks for all the replys.
Head gasket used is a Payon.
They are recommended by almost everyone here in South Africa.
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| 1200GXman |
Posted: 2006/11/7 20:08 Updated: 2006/11/7 20:08 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" Something just came to mind that I would like to share.
My cylinder head is bolted with the number 12 head bolts. As I understand, the torque specs of the number 12 head bolts is lower than the number 13 one's.
Is this not maybe why it is sweating?
Why did they change to a stronger head bolt back in those days?
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| Dodgeman |
Posted: 2006/11/7 20:14 Updated: 2006/11/7 20:14 |
No life (a.k.a. DattoMaster) Joined: 2003/6/27 From: Southern Tablelands N.S.W. Australia Posts: 8287 |
Re: head gasket "sweating" Quote: Poster: 1200GXman Date: 2006/11/8 6:08:52
My cylinder head is bolted with the number 12 head bolts. As I understand, the torque specs of the number 12 head bolts is lower than the number 13 one's.
Why did they change to a stronger head bolt back in those days? They did use different head bolts for GX models. This is from the factory competition tune up manual. |
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| Mildman |
Posted: 2006/11/7 20:21 Updated: 2006/11/7 20:21 |
No life (a.k.a. DattoMaster) Joined: 2003/9/2 From: SE Melbourne Posts: 3195 |
Re: head gasket "sweating" That could be a cause....I imagine all A14's will have head bolts with 13 on them - you should be able to find a couple of A14's in SA!
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| 1200GXman |
Posted: 2006/11/7 20:32 Updated: 2006/11/7 20:32 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" Now this is great!!!  It seems when my head bolts were replaced, they used the wrong ones. All mine is marked with a 12 on them. AGAIN I am now convinced this is why it is doing this. The GX head has more comp, that is maybe why it must have higher strength head bolts. The number 12 does'nt pull tight enough against the comp. Ok guys, now the other questions: Must I now remove cylinder head, clean up and use a new head gasket again? Or can I just remove bolts and use number 13 bolts. I have a idea it will be better to remove cylinder head and use new head gasket. Quote: That could be a cause....I imagine all A14's will have head bolts with 13 on them - you should be able to find a couple of A14's in SA! Mildman, you cannot imagine how many A14's are here in South Africa. It is like a Datsun plague here.  |
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| Dodgeman |
Posted: 2006/11/7 20:45 Updated: 2006/11/7 20:45 |
No life (a.k.a. DattoMaster) Joined: 2003/6/27 From: Southern Tablelands N.S.W. Australia Posts: 8287 |
Re: head gasket "sweating" Remove the head bolts one at a time & replace with the ones stamped '13' Torque each one up as you replace it & give the engine a good degrease so that it is nice & clean.
Then, just drive it. If it still leaks & you want it to stop, then you can replace the gasket, but if it stops leaking, then pat yourself on the back for saving yourself some un-necessary work.
Why were the head bolts replaced in the first place? There is no need to replace them unless there is something wrong with them, like if they were stripped, or broken or very badly corroded & deeply pitted. In a 1200 engine, they are not normally a consumeable item.
The '13' bolt was used in A14 & A15 engines, so they should be fairly readily available item either used, or new.
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| 1200GXman |
Posted: 2006/11/7 20:57 Updated: 2006/11/7 20:57 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" One of the head bolts was cracked.
It caused radiator fluid to seap through the head gasket to the outside. The mechanic I used at that time suggested the head gasket be replaced. He did it for us.
I just want to understand correctly.
Must I leave each head bolt as it currently is.
Then starting in the normal torque sequence remove them one at a time.
When removing one bolt, replace immediately with a number 13 and torque to the book spec until I have gone through all of them. And then of course get tappets set again.
Must I retorque again after 1000km ?
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| Dodgeman |
Posted: 2006/11/7 21:11 Updated: 2006/11/7 21:11 |
No life (a.k.a. DattoMaster) Joined: 2003/6/27 From: Southern Tablelands N.S.W. Australia Posts: 8287 |
Re: head gasket "sweating" Poster: 1200GXman Date: 2006/11/8 Quote: 6:57:02
I just want to understand correctly.
Must I leave each head bolt as it currently is.
Then starting in the normal torque sequence remove them one at a time.
When removing one bolt, replace immediately with a number 13 and torque to the book spec until I have gone through all of them. And then of course get tappets set again.
Must I retorque again after 1000km ? Thats the way. Take one out, then install the replacement & torque it down to the correct specs, then do the next one. Just remember that one bolt is different from the others & it must go in the right hole. [middle hole, spark plug side] Since the gasket has gone through many heating & cooling cycles, it would not normally need to be retensioned at about 1,000k, but for peace of mind, it would not do any harm if you ran the tension wrench over them again, then you can sleep easy. |
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| 1200GXman |
Posted: 2006/11/7 21:42 Updated: 2006/11/7 21:42 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" Thanks Dodgeman.
As I understand, I must also smear a little grease on the thread of each bolt when installing?
I will then drive it for 1000km and retention just to be save.
It just shows, if you don't do it yourself, it will not be right.That is why I try and do most of the stuff myself these days on my cars. If I don't know how, I will learn.
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| 1200GXman |
Posted: 2006/11/20 14:46 Updated: 2006/11/20 14:46 |
No life (a.k.a. DattoMaster) Joined: 2003/11/28 From: South Africa, Bloemfontein Posts: 1469 |
Re: head gasket "sweating" (New Update) Just an update.
I torqued the head again this weekend.
My head bolts are all definately 12's.
I set the torque wrench to 33 lb/ft and the torque wrench did'nt even move a millimeter when trying to torque.
It clicked before even moving.
Someone else said I must loosen then headbolts one by one and then retorque because they are coroded tight and might let me think it is torqued correctly while it is the corrosion.
Must I maybe set the settings higher on the torque wrench and try again?
What if I set the settings to that of the number 13 head bolts and torque the 12's to that settings?
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2006/11/6 21:47 
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