Tokendog's Head Re-Assembly. Q&A, thanks for looking.

[tokendog]

Hi Nicoclub.

I am in the process of putting my SR20DET's head back together. A few weeks ago it overheated and the HG blew, so I removed the head to check it for warpage, and to replace it with a metal HG, plus I want to clean up the engine bay and some of the parts. I am also replacing all of the gaskets, seals, etc. This is my first time undertaking some thing like this, so I thought it would be a good idea to make a topic where I could ask questions, post pictures, etc. and hopefully get this SR20DET back on the road.

I will do my best to search for the answers before I post a question on this thread, but hopefully you guys will have patience and help a fellow SR20DET/Nissan Owner out and help get him back on the road.

Thanks in advance, guys/gals. Your time is appreciated.

To start off, here's the car.By tokendog, shot with DSC-P200 at 2008-01-14

Here's the engine:By tokendog, shot with Canon PowerShot SD400 at 2007-12-27

Well I'll have more to post in the future and again, thanks for taking the time to read this thread and any help you can provide while I put this engine back together.

Token.

[tokendog]

The first question I have is this:

What is so bad about Cometic HGs? I ordered one because it was recommended to me, but then I started hearing that these HGs are not that great. Heavy Throttle and Enjuku both say it will be fine for up to 400hp and Enjuku says that is the HG they use in their National Drifting cars.

Is it really that bad? What can I do to make sure I do not have problems with it and are the problems bad enough that I should bother trying to sell the one I have and getting a better one like Cosworth?

I am running 10psi on a T25 and daily drive it. I will also be using ARP head bolts instead of stock bolts. What do you guys think? Worth selling the Cometic HG and going with some thing better?

[Hijacker]

If all you plan on doing is running 10 psi on a stock T25, you can stick with a stock headgasket and never have any problems. especially is you're using ARP hardware.

The issue with cometic headgaskets is that they seal for crap. Part of the problem is due to poor QC. For every one person I hear that has good luck with their headgaskets, I hear of 5 others that started leaking.

The other issue is preperation. All metal headgaskets need to have the block and head checked and decked for straightness, but the cometic seems to be the most finicky.

Also, this is a bit of handed down experience for me. One of the best mechanics I know of has had experimented over the years with L-series metal headgaskets. He has found that when he retorques the headgasket down after the initial break in, the gasket doesn't leak. But if doesn't do a retorque, the gasket does leak. Now, I don't know what manufacturers he had used as this has been something he's noted over the decades he's been wrenching.

http://jdm-insider.com/Blogs/Eric/?p=386

There's a comparison blog comparing the cometic, factory, and cosworth 4G63 (evo motor) headgaskets. As you can see the cometic just doesn't have the same sealing qualities as the factory and cosworth gaskets.

There are quite a few threads on these boards concerning cometic and it's questionable quality. I know some who argue for cometic and say it's the best bang for buck and they have always had good luck with it. I know others that have never had one seal properly. The issue comes down to who did the proper preperation and follow up maintenance.

[tokendog]

Well I definitely don't want it to leak again so I may try to get another head gasket. I know I am going to lose money on selling the Cometic, if I even can, but I do not want to have a leak later on down the road. I am trying to do it right this time.

I had a question about cleaning the short block - I did not pull that to have it checked for warpage, but the machinist who looked at my head and cleaned it up for me said there was no warpage on it at all. So my question is this, to clean up the old gasket and crap that is on the block, should I just use emery cloth and lightly buff it or is there a better way to make sure its clean and prepared for the HG?

[Hijacker]

I usually use 3M roloc discs. They're designed to clean off gasket material but not remove the metal.

[tokendog]

Well, worked on cleaning up the engine parts a little bit and also pulled the wiring harness.

Here's the beast. I am sending this mess to wiringspecialities.com, I think, in order to make sure its wired up properly so that I don't have any electrical issues with my upper wiring harness. The lower wiring harness looks like crap also, but its harder to remove so I am hoping its not the source of some of my problems.



Here is the Head when I first pulled it and before it was sent to the machine shop:



Here it is afterwards:



The machinist said it wasn't warped. He went ahead and cleaned it up for me though. He thinks it had dirty radiator fluid and when it was flushed with new fluid, it left a few spots where the gasket blew apart. There was only a couple of small places where the gasket blew.



I had purchased Purple Power to clean the parts but then I found out that Purple Power eats at aluminum. So I decided to use Dawn dishwashing detergent instead. It works really well, not as well as Purple Power, and it takes a little more elbow grease, but it gets the job done. This piece was caked with oil when I started and it looks pretty clean now.



I am wondering whats the best way to clean parts with electrical connections such as this... I am assuming a brush and soap? Any ideas?



Also, I was wondering if removing the TPS and not putting it back in the right position would cause any problems??? How sensitive is it to that kind of stuff?



Going to try and find those 3M Doloc pads that HiJacker mentioned (where can you find those? auto parts stores?) and clean up the pistons/block with it. I also want to clean up the wires/hoses/pipes in the engine bay to make it cleaner and easier to work on.

What are some of the items you can delete from an SR20DET? I read there isn't an EGR, but what else can you delete to free up some room in the engine compartment?
Modified by tokendog at 11:10 PM 4/8/2008

[duffman1278]

Yes, removing the TPS and not putting it back the way it should be will cause issues at start up. However its easily fixable with a multimeter. Just readjust it before you start the motor with a multimeter to .37V at closed throttle.

I've heard that putting your electrical plugs into like a bucket of degreaser will work.

The doloc pads can be purchased from like mcmaster carr online if you'd like.

[tokendog]

I am still debating on whether or not to go with the stock head gasket with ARP hardware or to purchase a Cosworth MHG. I have a Cometic HG at the moment and a stock HG. I have pretty much decided the Cometic HG is not going on and I have been reading that the stock HG with ARP hardware is really really good for low boost applications which is what I am aiming for at the moment.

The most I'd aim to boost at is 12psi on the T25. Daily boost will be around 8 to 10 psi.

What do you guys think? If it were your personal decision, would you go with what you already have (stock HG and ARP studs) or wait a little bit longer and get the Cosworth?

I do not mind doing another head pull a few months down the line if/when I decide to run higher boost/bigger turbo.

[240life]

I personally would wait and get the best headgasket possible, i hate messing with that stuff. To do it twice in a matter of months just seems crazy to me.

[duffman1278]

Just get yourself a nice well known HG like apexi or something, better than spending two times for 2 different HG's.

[positron1]

Same situation, got a Cometic HG holding down the floor at my place too!

[tokendog]

Ok well, between work and school, I have not got much accomplished since my last post but I am hoping to change that soon. I purchased a tool to remove the gasket from the block (had a lot of the old composite gasket left over). Its a 3M Roloc Pad designed for aluminum. I also ordered the white one, which is supposed to be a softer grit, and am hoping this will work. Are these the right pads to use on aluminum? I heard green is what you use on iron. Please let me know before I get to it.

I am also using a cordless drill because I do not have a die grinder.





In the meantime, I also got a new daily driver for me and my wife. I wanted a Mazda Speed but my wife did not like them and I already have a turbo car, so she said no. Plus she drives this more than I do. I still have my 300zx. Anyways, this is off topic, but here are pics.







and the interior. I love the interior. We were also looking at an 08 Sentra, but my wife did not like the exterior of the Sentra nor the interior, and I agree. I honestly can't stop checking out the color-combo on the dashboard.



Its a pretty quick car - especially with the Sports Trac Transmission, which I like because I prefer manual, but my wife is nervous about it, so she uses automatic...with Sports Trac, I can use manual when I want and she can use automatic...plus its electronically controlled, so you can't mess up the transmission because it wont let you upshift or downshift in to a gear unless the RPMs are within a safe range.

The color is like a graphite gray and its actually a lot smaller than it looks in the pictures, but it has a lot of interior room. Plus it has over 12 cupholders altogether....crazy!!! I've already checked (of course) and there is a turbo kit for it that puts it up to around 230-250HP...very nice :> Of course I can't touch it until the warranty expires, but never too soon to start planning, right?

[tokendog]

Bringing this back from the dead as I will have more questions in the near future as I finally find the time to finish putting my car back together.

Since the last time I posted, I've managed to put the head back on and all the internals on the head, etc. etc.

So now I am working on the manifolds and wiring/hose routing and just cleaning up the organization of the engine bay.

I was looking at the FSM and it says torque the bolts that hold the upper and lower intake together to 15lbs. This is in the S15 FSM. I'm just wanting to make sure. 15lbs is correct?

Also, you only use a paper gasket on this, right? No need for liquid gasket or any thing of that nature?