blown head gasket?

[zcar?]

so i think that i may have a blown head gasket....... i need to know what to look for, like my oil that looks like a milkshake, and lots of water coming out of the exhaust..... it sounds like one to me but what do you guys think? are they hard to replace? expensive? thanks

Jeremy

[roger.svoboda]

If your oil looks like milk and water is coming out the exhaust You have a blown head gasket. not particularly hard to replace but you do need the proper equipment. Torque wrench must have. Way to lift the head or some strong buddies. I took off the head with the manifolds and turbo off an 83zxt. My son and I were able to lift it off the block with out too much dificulty. There are two schools of thought on whether to take the manifolds off with the head in place or just take out everything. I lean to the take the head off with manifolds in place cause not easy to get at the bolts to loosen the manifolds. Clean all gasket surfaces thoroughly before reinstallation. Make sure head bolts are clean and go freely into the threaded holes. Only way to get correct torque is with clean lubricated bolts. MOST IMPORTANT - stick a piece of wood like 7" long by 1.25" thick down between the timing chain to keep the tensioner in place. If you fail to do that you need to take off the timing cover and even more work ensues. Drill hole in the wood and tie some rope on it so you can pull it out when head is back together. A piece of 1x4 cut as above works well. You don't need it to be wedge shaped a rectangle will do. If you can't get it down there trim the 1.25 dimension down a little until it goes in snugly with a little force. the wood will crush enough and not damage anything metal in there. If you are not a particularly experienced wrench I'd get some help and/or advice. Any z clubs in your area? usually someone is willing to advise and help if asked. You should have good selection of sockets, open and box wrenches etc.

[z-ya]

Find out why the gasket blew (warped head, etc.).

 

Since the oil has been contaminated with water, once you get the new head gasket in, drain the oil. What I've done in the past is then our a couple of quarts of clean oil over the cam, rocker arms, and timing chain while the plug is still out. Change the filter, put the plug back in and fill it with oil. Run it checking the oil for water. Remember, the oil will still have some water in it. Let it come up to temp, then change the oil again, and you should be all set.

[wardie]

You need to be aware of another problem L engines suffer from which looks exactly like a head gasket problem. I've had this issue twice on my L24E.

 

If your cooling system has not had good quality coolant (anti-corrosion) for most of it's life, it can corrode the aluminium back of the water pump/timing cover. Eventually it can cause a pinhole in the timing cover and fill your sump up with coolant when the engine is hot.

 

I replaced my head gasket the first time twice and had the head tested for cracks and straightness before someone suggested the timing cover. I got it welded but within 9 months it happened again. I replaced my timing cover and all is sweet.

 

Checking your compression will help you. If they test roughly all the same suspect the water pump housing.

 

BR

 

Wardie

[zcar?]

thanks for all the input. so far i took it all apart and then checked the head for warpage but since i diddnt have a good straight edge i diddnt get a good measurment so i took it down to the machine shop and will get it back tommorow. so we will see how it looks, the timing cover looks like new so i dont think thats the problem, what are the chances of the block being warped? and the timing chain needed to be replaced so while i was in there i decided to that so hopefully it will be fixed and running good

[zcar?]

so i need a new head now they found 7 cracks in it, one between each valve and a huge on going from the exh. valve to the coolant hole on cyl 3. so where would be a good place to get a head? junkyard? and is there a better head than the n47? more durable? thanks guys

Jeremy

[z-ya]

The N47 is what you want, mainly because of compression ratio and exhaust port shape. The N47 has round exhaust ports (with liners), and the N42 has square (no liners). Other than that they are the same. So if you have a round port header, stick with the N47. Better yet, find a Maxima N47 (MN47), it will give you slightly higher compression ratio. It also has a more modern combustion chamber shape (peanut). A P79 or P90 head will lower your compression ratio.