Pulled the head, looks nasty? (56k no way)

[KlanjacOFF]

Well I've been ordered parts for my RB25 now for a good two months now and the majority of them are here so I decided to get off my *** and start working on tearing it down somewhat. I pulled the head off and I dunno....it looks nasty, lots of oil residue everywhere. This is my first time doing any "motor work"and I don't know what things should look like ya know? so I wanted to see what you guys have to say. Is this normal looking? The only reason I am posting this is I got my complete motor set from someone local, whom had swapped it into his 240sx and then pulled it out. The only problems was that the turbo was blown(not a big deal, planned on upgrading anyways) and I couldn't check compression because the engine was not in the car, which I was very uneasy about but my friends(that were friends with him) assured me he was a trustworthy guy. So I bought it anyways and now see this. Just need a diagnosis as what to fix possibly IF this is not normal, looks inconsistent. I want to do it right the first time and not have to worry about anything so yea. Here is the pics. Oh and the engine has been sitting for 6+ months

So clean

[Bluefire]

Motor looks to be in good condition. Might be a bit of oil residue left from the blown turbo, but other than that it looks good.

-Bluefire

[Darius]

I thought the same thing. The first thing I noticed was how clearly the cross-hatch in the bores can be seen.

The head gasket always looks nasty but that's what happens with the organic gaskets. What kind of head gasket are you going to put on there when you reassemble it? And why exactly did you disassemble it in the first place? Are you putting forged rods and pistons in it?

One other thing... is there any assembly lube on the cam journals?? They look dry as hell. Don't even think about trying to start that engine without smothering those things with assembly lube.

[DriftingisLame]

I thought the same thing. The first thing I noticed was how clearly the cross-hatch in the bores can be seen.

The head gasket always looks nasty but that's what happens with the organic gaskets. What kind of head gasket are you going to put on there when you reassemble it? And why exactly did you disassemble it in the first place? Are you putting forged rods and pistons in it?

One other thing... is there any assembly lube on the cam journals?? They look dry as hell. Don't even think about trying to start that engine without smothering those things with assembly lube.

Darius is right, pour oil over the cams, or cake some assembly lube on them before you put the covers back on and fire it up. The lobes look to be in great shape though, there's just no oil on them because its been sitting for so long.

Also, it may look nasty, but the stock headgaskets make a mess like that after being smushed between the block and head for so many years. All of the carbon and crap in there may look nasty, but it also assures you that the motor has likely never seen above stock HP or anything other than factory electronics. Thats a GOOD thing!

I think you're motors overall in great shape. If you're not shooting for 500+ hp, get yourself a stock gasket set, and drop your head off at a machine shop for a good clean and resurface.

Good luck!-Max

[Darius]

[KlanjacOFF]

haha, Thanks guys that makes me feel alot better. I took the head off because I'm taking apart the block. My crank can get the new collar put on and then the block will be hot tanked and decked for the cometic headgasket with ARP studs. And thanks for the tid bit on the cam journals and having to grease em up. I would have never thought about it, but my friends would have probably caught it. Anything else special that I need to know about disassembling and reassembling the block? Should I treat it as a rebuilt engine basically? As far as lubing all the rod bearings and breaking it in? I'll be putting new rings on as well, since I dont think you can re-use the ones coming out.

[Coolwhip]

yea plus 1 on the head being rather clean.

[l0nestar]

I would question the cometic head gasket.

Cosworth or Tomei for MLS or just stick with the OEM Nissan depending on your power goals.

If you are serious about an MLS gasket, make sure to get your head + block decked / surfaced! (Right Darius! :-D)

[Coolwhip]

If you are serious about an MLS gasket, make sure to get your head + block decked / surfaced! (Right Darius! :-D)

rub it in time!

[Rellik27]

looks real clean

[Darius]

I would question the cometic head gasket.

Cosworth or Tomei for MLS or just stick with the OEM Nissan depending on your power goals.

If you are serious about an MLS gasket, make sure to get your head + block decked / surfaced! (Right Darius! :-D)

rub it in time!

You ruthless peckerheads!

If you use the Cometic MLS, both surfaces need to have mirror finishes (literally) in order for it to seal properly. If you're aiming for less than ~400hp, go with the OEM gasket. Otherwise, go with the Cosworth.

[KlanjacOFF]

Well damn, I'm so tired of buying parts I'm not going to use. Wonder why the Cometic is so bad. I will probably buy the cosworth head gasket then, unless the OEM one can handle mid 400 ponies on pump. I take it you had horrible luck with the Cometic Darius?

[KlanjacOFF]

Two more things...

Is it a necessity to put new rod and main bearings in while I'm doing this whole thing? I see Cosworth sells them

And

What size Cosworth headgasket should I get, they have 1.1 and 1.5.

[l0nestar]

Well damn, I'm so tired of buying parts I'm not going to use. Wonder why the Cometic is so bad. I will probably buy the Cosworth head gasket then, unless the OEM one can handle mid 400 ponies on pump. I take it you had horrible luck with the Cometic Darius?

I'm going to break this down into replies per sentence:

1. We all are..

2. There was a thread around here comparing common MLS head gaskets with surprising results. They don't seal quite right under load. Also, like Darius said, with the Cometic, it _HAS_ to be a mirror finish or it won't seal.

3. Yes. The OEM should be fine. Seriously.

4. Darius could / should tell this better than I can. Suffice it to say that he only had the head decked, not the top of the block (Correct?) and it did not seal for crap.

[l0nestar]

Two more things...

Is it a necessity to put new rod and main bearings in while I'm doing this whole thing? I see Cosworth sells them

And

What size Cosworth headgasket should I get, they have 1.1 and 1.5.

Not "necessary", but I would do it since you are replacing all of the gaskets. You are already spending quite a bit on machine work and parts, what is another $150? (

I got new rod and main bearings when I had my collar 'fixed'.

I can't comment on the different HG's - I would suggest contacting Cosworth directly about it - or just go with the OEM and be done with it...

[DriftingisLame]

Take a look at the fat steel ring that surrounds each combustion chamber on the stock headgasket. I really dont see how that would give, I kinda doubt it would be much weaker than an MLS gasket. Even if it is, the stock gaskets always seal properly.

I'm probably always going to stick with a stock gasket. Thats just me though.

I'm pretty sure Carl H uses a stock gasket, 400+ hp hasnt broken it. In fact, all RB's, whether its a 20/25/26/30, have hit 450 whp with unopened motors. I've never seen a stock headgasket break, has anyone personally seen detonation kill a stock headgasket?

[Darius]

I'm also going to break my replies down into short hand:

1. lonestar- my first go-around I didn't deck the block. The second time I decked both and it sealed...to be continued.

2. If you have the motor completely apart already, just do the bearings. They are cheap and easy insurance and cake to install if your crank still looks good.

3. Stock gaskets hold a lot of power. Detonation kills them relatively easily. There are two loooong threads on SAU of all the Aussies that have blown their stock RB25 and 26's up for varying reasons. Most stem from running unknown tunes and impulsively increasing boost for that fateful pull. Too long to cover here.
Modified by Darius at 7:27 PM 3/24/2008

[DriftingisLame]

I searched a bit on the SAU forum, and I cant find the threads you're talking about.. I'm curious to read what they have to say about the stock gasket. If you'd be so kind as to link me to one of the threads, I'd appreciate it.

Thanks-Max

[WI_S14_Goldie]

it looks like some of your valves maybe bent... not sure if the cam lobes are pushing them down or what...

[nisstek]

it looks like some of your valves maybe bent... not sure if the cam lobes are pushing them down or what...

[240z4u]

IMO headstuds and stock gasket are all you should need.

I personally know of a guy who was spraying an RB and stuck a hole in a few pistons before the headgasket blew on his RB25DET.

I really don't feel that MLS gaskets are needed for stock internal motors, if your building one it only seems logical.

Evan

[KlanjacOFF]

Alright cool, thanks for the info guys. I will probably just use the stocker I have then. Not worried about detonation, as I am confident in my abilities to tune.

Most of you bro chad chills using the cosworth bearings? Doubt the OEMs can be found.

[l0nestar]

I thought it was 'Chad Bro Chill'

I used King bearings, but I think Clevite makes some. I used King and I'm happy with them.

[Darius]

I searched a bit on the SAU forum, and I cant find the threads you're talking about.. I'm curious to read what they have to say about the stock gasket. If you'd be so kind as to link me to one of the threads, I'd appreciate it.

Thanks-Max

http://www.skylinesaustralia.c...iston

Enjoy! It's hysterical what some of the guys have done. It is like they don't even care.

[AWDB12wagon]

I'd say that stuff burned on top of your pistons is oil leaking from valve stem seals. You may also want to have the valve guides checked out, the exhaust side is usually the worst. Although those leaks look like they're on the intake side??! Odd.

[Darius]

Probably oil from the PCV system. Common occurrence, install a catch can and it'll clear up.

[KlanjacOFF]

Well, I finished disassembling today and the piston land on piston 1 and 6 were cracked....several times. I was really disappointing and pissed because now I gotta save up for new pistons and put the build back even further. Pics will come soon, I want to see if you guys think my crank is ok or if it needs to be machined. Didnt see any scoring on it but my eye is not trained soooo, yea. bad day

[bmadd2402]

that sucks dude. My pistons looked like that, and I just worked them one at a time and polished them up. I put them at TDC 2 at a time, covered the others and went to town. I installed a stock gasket, and ARP studs and called it a day. if ring lands are cracked, will it show on compression or leakdown tests?

[bumblebtuna]

now I gotta save up for new pistons and put the build back even further.

been there done that. lol

the crank is going to be a short snout man. no doubting that.go ahead and order the collar if you plan on alot of boost

[Darius]

LOL I am the former VP of "been there done that". Better join the NRRBA so we can keep track of when you officially became NR. Who knows? Maybe you can become the president some day!

zerothread/312978