Help.. Overheating etc...

[91blackgtr]

well we started to do a compression test and coolant sprayed out of the spark plug for number 5.

[nbskyline]

Head gasket?? Or worse???

[nbskyline]

http://forums.gtrcanada.com/picture.php?albumid=2&pictureid=1

This was pouring out my down pipe!!!!

[nbskyline]

What thickness metal head gasket?? APR studs and gasket kit.....Anything else??? Do you think it is just the head gasket?? Block and head ok????

[mcfly]

you are going to want to check both the block and head for warping when you get it out.
1.2mm is stock thickness.

[Skym]

From what I understand, headgasket commonly fails on 5th, 6th cylinder, as they are closest to firewall and the result is those cylinders get the hottest and head warps. More so if the cylinders run lean. Shortblock can crack around those cylinders if it gets hot enough. So clean the deck of shortblock and look for cracks. Cracks look like this -

http://2.bp.blogspot.com/_vhpEGyEVhes/RpbIrW-AxzI/AAAAAAAAACE/7epF2ZiE6mk/s1600-h/IMG_0350.JPG

http://3.bp.blogspot.com/_vhpEGyEVhes/RpbIrm-Ax0I/AAAAAAAAACM/FqRPvdxa1is/s1600-h/IMG_0359.JPG

Nismo bore out the watergallery's in N1 shortblock, N1 head to help solve this heat build up / cracking problem. It's a common problem with straight 6 engines.

The dude from Japan in this link with RB26, did the bore out of watergallery's mod around 5th, 6th cylinder with stock shortblock and it helped to solve the heat problem -

http://www.jdm-option.com/eng/feature/06_02/r32.html

Head (made of aluminium) will warp before shortblock (made of iron) if engine overheats. Also change welsh plugs on front and rear of head, as they are known to pop / leak (that's what they are designed to do) when there's excessive pressure in cooling system from a fully closed thermostat problem. Higher pressure radiator cap with stock headgasket can make cooling system leak at welsh plugs, headgasket, radiator top or bottomtanks, waterpump, etc.

Send head to cylinder head shop and get them to skim the head to make sure it's square before fitting new headgasket. Also replace welsh plugs with upgraded brass? welsh plugs. Common mod is to upgrade welsh plugs on Group-A RB26 shortblocks, head, etc. They also paint the underside of cylinders with white paint to stop chunks of iron falling off and entering oil system. Group-A shortblock is basically a modified N1 shortblock.

[nbskyline]

Any way to check the block while in the car?? I really don't want to pull the whole thing

[nbskyline]

It is a headgasket for sure!!!

[nbskyline]

[nbskyline]

Check the head for sure!! Should I be ok with just that?? I will check for a crack in the block after I clean it up, or do you think I still need to pull it!!:-(

[M13]

It is a headgasket for sure!!!

Make sure you skim the head.

[nbskyline]

How much of a skim??

[91blackgtr]

give them a call tomorrow, then start the parts ordering lol

[mcfly]

Check the head for sure!! Should I be ok with just that?? I will check for a crack in the block after I clean it up, or do you think I still need to pull it!!:-(

nope, just as you are cleaning the block check it closely. you could even magnaflux in the engine bay it if you really wanted.

Like the others said check to make sure the head and block are still true, if not they need to be decked.

[Skym]

Just clean/check the deck of shortblock for cracks. If no cracks, don't need a new/second hand shortblock. In somecases it's easier to bin engine and fit another low km second hand stock engine (replace headgasket) or new N1 engine with N1 shortblock, etc. With N1 engine option, all the sensors, etc are new and has the watergallery, etc mods and raises value of car. But it's not cheap. Also any shortblock can crack if engine is not left too cool before flushing cooling system.

With skimming, as far as I know they check the flatness of the deck of head with like a ruler from corner to corner (cylinder 1-6) and then straight along the deck off head from cylinder 1-6. The warping should be very noticeable, as there is a gap between ruler edge, deck off head. Then they skim enough off deck to make deck straight again.