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PostPosted: Fri Sep 14, 2018 6:39 pm 
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Howzit guys

Im from South Africa and busy building a turbo suck through engine. The engine blew the first original head gasket out and i replaced the gasket with another original one. This gasket also blew out.
I then skimmed the cylinder head and put a copper gasket in. This gasket is a solid copper plate. I sprayed the gasket with the proper copper tack sealer but there was still a leak.

Is there anyone with experience regarding copper gaskets?

I did not skim the block. But will do this now when assembling everything now again. The car still has high compression pistons in and with the closed chamber head and the bit thicker gasket the compression ration is around 9.2:1.

Any help will be appreciated.

Regards
Jason


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PostPosted: Fri Sep 14, 2018 10:18 pm 
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did you anneal the copper first?

https://www.youtube.com/watch?v=EyXBlhuBoAk


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PostPosted: Fri Sep 14, 2018 10:21 pm 
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The shop where I bought the gasket from said that it was annealed.


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PostPosted: Mon Sep 17, 2018 11:58 am 
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compression too high at 9.2, need 8.0 for it to work well and not go over 8 psi.


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PostPosted: Mon Sep 17, 2018 1:16 pm 
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While I agree the compression ratio is quite high for a turbo application in an L-series, I don't think this is the root cause for a leak from your copper head gasket.

You don't mention if this is a compression leak or coolant or oil leak however I will make the assumption that it is a compression leak as it seems to be cause of the first two failed gaskets you mention?

I would ensure the gasket is annealed EVERY time the cylinder head is removed and replaced and I would strongly consider having the cylinder block machined for a steel wire o-ring groove to ensure the compression pressures are better contained by the clamping force of the cylinder head. I would also consider using head studs / nuts to fasten the head to the block (not bolts). There is some research you're going to have to do here, it's not easy to make a specific recommendation....definitely start with the basics, block (and head) flatness and surface finish, o-rings and head studs would be my starting point.


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PostPosted: Mon Sep 17, 2018 8:58 pm 
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Good day people

The standard gaskets that was blown out due to cylinder pressures. i havnt had a chance to take the head of again to see if the copper gasket failed or got blown out by cylinder pressure, but i dont think so. Im struggling with sealing around the water channels so that water do not end up in the cylinders. So before i go to the extremes of fitting orings etc, i just want to make sure i try all the other basics and do it right.

So to make sure the head gaskets seals properly around the water and oil passages, what can i do? I read somewhere that they recommend spraying of the copper gasket sealer once and let it dry. Then the next day just before fitting of the gasket, they said to spray another layer of the copper gasket sealer. There was also another guy that said to put another (better sealer) around the water holes on the gasket to help with sealing them off. Then fit the gasket and head and torque. after torqueing the head, dont drive the car, but only let it get up to temperature (this is to help cure the sealant?) with idling. Let it cool down and retorque again. only after this go and drive the car.

Any inputs regarding the above mentioned method would be appreciated.

I must say I think I made a few mistakes when fitting the copper gasket the first time. I didnt clean the surfaces of the block and head with a solvent to degrease properly. And also i drove the car directly after installing the new copper gasket with one layer of the copper sealer. What other sealers can I use?

Regards
Jason


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PostPosted: Tue Sep 18, 2018 12:00 pm 
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Well, from my experience from the early 90's on Ford V8's (iron block / iron head), we used to use just the slightest smear of RTV silicon gasket sealer around all the water and oil passages to seal the fluids and never had internal or external coolant or oil leaks; the RTV is smeared on as thin as possible and gasket installed when it is tacky (about to cure). We also used two coats of Hylomar copper sealant spray (both sides) with time to let them tack off between coats, installed dry.

I also agree with the warm up / cool down / retorque (which should also be done with a non-copper head gasket anyway) cycling as well. Yep, you can't just bolt it on and go for a thrash (not if you expect it to last....) - well OK a Top Fuel engine can get away with it but those things don't run coolant and any oil is consumed in the combustion process along with the ridiculous amount of nitromethane in the (maybe) 2-3 minutes total they run between rebuilds!

As with most engine build tasks, it's a good idea to have an attitude of being as scrupulously clean as possible when preparing any parts however cylinder head, block deck and gaskets are particularly critical and that was my assumption from my last note.....you can't get it too clean!


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PostPosted: Tue Sep 18, 2018 4:47 pm 
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Thank you Pista

Thank you very much for the help. I dont have too much experience with rebuilding engines. Only learning to do it now. So I have no experience with copper gaskets. Will make sure everything is as clean as possible and see if i can put some other sealer around the water and oil holes.
Do you think its necessary to skim the block aswell? The surface still looks decent, but it is an old engine and you can see some marks here and there.


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PostPosted: Wed Sep 19, 2018 3:14 pm 
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Id be weary of head going soft over the years


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PostPosted: Wed Sep 19, 2018 10:28 pm 
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Location: Melbourne, Vic
L18Skyline wrote:
Thank you Pista

Thank you very much for the help. I dont have too much experience with rebuilding engines. Only learning to do it now. So I have no experience with copper gaskets. Will make sure everything is as clean as possible and see if i can put some other sealer around the water and oil holes.
Do you think its necessary to skim the block aswell? The surface still looks decent, but it is an old engine and you can see some marks here and there.


Considering if the engine is still in the car, I'd not worry about getting the block deck skimmed as it would mean removing everything and disassembling the whole engine - in that case you'd probably want to be changing out pistons (ideally to lower compression to suit the turbo system) and reconditioning everything while you're at it..... I would, however, clean the deck meticulously as discussed. What I would definitely do is check cylinder head gasket surface for flatness....referring to the trusty Nissan L16 & 18 Engine (1973) Factory Service Manual (thank you Nissan Motor Company.....), the procedure set out in the picture below (on the left hand side of the page). It involves using a straight edge (a steel rule should be OK for this) and feeler gauges to ensure no part of the gasket surface of the head has a clearance from the straight edge of more than that in the table..... If you're not sure, or if there is some indication of warpage of the cylinder head surface, I'd be getting it double checked at a reputable engine reconditioning workshop - if there is an issue, you'll be going there anyway!

While you're there, you could get the cylinder head hardness checked, like 'd' suggested in the post above, however each engine shop may have an opinion on what specification to use for a Nissan engine (I'm not sure....) and the FSM doesn't call out a specification. Typically, however, if the engine has NEVER been run overheated, you'll find the head material hardness will be fine....


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L18 Cylinder Head Flatness.jpg
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PostPosted: Thu Sep 20, 2018 3:14 pm 
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If there is warpage on your head consider an open chamber L series head
a long time turbo L series guy recommended them over closed chamber heads.
They are cheap heads to find still even reco anyways
http://dimequarterly.blogspot.com/2012/ ... -head.html


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PostPosted: Thu Oct 25, 2018 4:59 am 
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Good evening people

I have not had the time the take the head off again. Was looking for a new set of head bolts because the old bolts did not want to torque nicely and felt like they were stretching? The problem is I could not find any new head bolts for the L-series engine in South Africa anymore. Now i was wondering what other head bolts I can use? Will head bolts from the CA18 or SR20s not work on the L18?

As I measured the L18 bolt holes it gave a 10mm thickness. The length of the shorter head bolt must be around 120mm and the longer one around 140mm (the lengths i did not measure, only the thickness)

Any help would be appreciated.


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PostPosted: Tue Oct 30, 2018 7:02 pm 
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go to a bolt shop, you can get better quality replacements even invest in arp units for this kind of build it needs it.


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PostPosted: Tue Oct 30, 2018 10:56 pm 
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Location: Melbourne, Vic
Yes, I would invest in head studs for this build, too.

ARP Kit #: 202-4201 would be a good place to start.


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PostPosted: Thu Nov 08, 2018 11:01 pm 
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Good day people

Just an update on the L18 turbo.

I got new head bolts from the engineering department in town. It is basically stand hex cap bolts that fits the thread in the block and works nicely.

I tested the bolts (removed the old bolts and fitted the new ones without removing the head) to see if the new bolts cant seal the gasket with the correct torque settings, but unfortunately it did not. So i removed the head and cleaned the copper gasket, block and head surfaces (with acetone) and put some new copper-tack on the gasket. I torqued all the bolts and when it reached 85Nm of torque the one head bolt hole in the block (the rear hole with the dowel) stripped.....

So the engineering shop tapped the hole in the block again and hopefully in the next week or two i will fit the head again to see if i can get to seal the cylinders and not leak any pressure.

What i can see is that the copper-tack sealant i use become quite hard when it heats up. So i will make sure i don't rev the car hard while this sealer sets and hopefully there wont be any problems!

Thanx for all the advice so far.


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