Blown Headgasket

[ka-t_2_be]

I recently picked up a 1993 240sx with what the guy claimed was a blown headgasket. The symptoms are as follows; Lots of white smoke out of the muffler at start up, only dirves for short distances, then gets pretty bad. My questions are; is this only a blown headgasket? What else could cause this? And, I have taken KA24DE heads off before, but only outside of the car. Are there any tricks or tips to replacing a headgasket with the engine in the car? I have never replaced a headgasket, so I am also wondering, how smooth does the surface have to be for the headgasket to seal properly, and is there a sealant to use also, or is it just the gasket? So, I guess basically, my main question is, can someone please give me directions on replacing a head gasket on a KA24DE inside of the car? Thank you for whatever help you can give.

[DjPantsSpecR]

sounds like a blown head gasket, but with an aluminum head and an iron block, overheating these motors only a few times can start to cause warping.

pulling the head off in the car is easy. ive done KA headgaskets what seems like a million times, so i can completely remove and put back on a head in 4 hours. my first time it took me about 8 hours. no special tips or tricks, you'll handle it just fine if youve already pulled a KA head off

but when you get that head off get a straight edge and lay it across the head diagonally, sideways, lengthwise, every imaginable way, and check for warpage using a feeler gauge. im guessing you should get it at least decked, but you should be just fine otherwise

[ka-t_2_be]

Maybe a noob question, but i've never done any kind of machining. What exactly is the process of "Decking"? If I want to keep the engine in the car, can I deck the block? I may just be not understanding something, but it sounds like I would have to take the engine out for this. If it feels pretty smooth can I just do the cleaning and gasket, or is decking mandatory? Thanks.

[DjPantsSpecR]

you can bring the head to any machine shop, and they physically machine the head down flat. its cheap too, maybe 30 bones, probably around 20

as for the block, you can check it for warpage, but i doubt anything will be too far out of spec. the headgasket should physically take up that area. you can get a big flat block of wood and some sandpaper to try and smooth things out. i woulodnt bring my block anywhere to be decked

[ka-t_2_be]

That answers most of my questions. There are a few more however, is there any kind of sealant used? Or do I just lay down the headgasket and bolt the head back on? Do I need new headbolts? What other parts will I need besides the actual gasket? Thanks for everything so far.

[zippitta]

It would take hours to even affect the block with sand paper...lol.

Your block will be fine. But as ^ said check your head real good.

[TheOne]

headgasket, exhaust/intake gasket(most likely damaged by then), some goo(rtv sealant) for the upper front timing chain cover and the front/back "u" lookin parts of the valve cover gasket.

[ka-t_2_be]

So, I understand that I need to put some sealant on the upper timing chain cover and the little half circle things. But, do any of the gaskets themselves get sealant? Does the actual headgasket get any sealant, or do I just place it between the block and the head, then bolt the head on? Im gonna guess that the intake and exhaust gaskets dont get any sealant. Also, would gasket sealant work for the upper timing chain? Or do I have to get RTV? Also, where can I get some RTV if it is required? Thank you for all of your help, sorry if it seems like im retarded. I have torn the KA apart, but this is my first time putting one back together. But hey, gotta learn sometime right?

[ka-t_2_be]

Anyone??? Sorry if im repeating the same question, but I just want to get my car back together. Thanks

[TrueSlide]

Head gasket get NO SEALANT. Exhaust gets no sealant, I would put sealant on the intake gasket. Any thing that the headgasket comes in contact with = no sealant. Headgaskets normally come with a sealant type agent on them. Just be sure you torque the headgasket correctly, in order and by the steps.

[ka-t_2_be]

Thank you, that is exactly what I was looking for. Thank you very much.