I have a 1995 nissan 4 cyl. Water pump went out and it overheated. I changed the water pump and it has been fine since then. Now the temperature gage goes 3/4 to all the way hot before the engine begins to cool down. I changed the thermostat and thought that would fix it. The next time I drove it it did the same thing (went to 3/4 of the way high). Now the gage goes nearly all the way to hot and it doesn't look like the thermostat is opening up. Any ideas on what else it could be?
Check your compression on each of the cylinders. When the truck overheated, it may have warped the cylinder head, meaning the gasket isn't sealing well.
Do you have bubbles in your coolant, white "smoke" in your exhaust, or milky oil (meaning coolant in your oil)? Any of these symptoms COULD mean that your head gasket needs replacing.
I think the easiest way to diagnose this, at least as a first step, is to check the compression in each of your cylinders. If you have lost compression on adjacent cylinders, you can bet the gasket between those two cylinders went, or the head is warped.
These KA24Es have very tight cylinders -- they started life as 1.6L engines and were "bored and stroked" in the design phase as much as possible. From what I hear, the cylinders are so close, you can't over-bore one during a typical rebuild. No oversize pistons are available. If that's actually true or not, I don't know, it's just what I heard. But either way, you need to check the compression because something might have warped (the cylinder head). In this case, you may be able to get it milled if it's slight and be okay. If it's a major warp, you may need a new cylinder head. Check the head and block for warpage if you get into it that deep.
jadcock,
thanks for the reply. I check it out and it something with the headgasket, and a warped head. Looks like it's gonna need to be replaced. Now that's something I don't want to go into myself, what's what usually run?
There is a particular figure assigned to this, but I don't know what it is. You can call a local garage to find out how much labor is suggested for this job. They'll say, "it's a 4.6 hour job" or something similar, and they'll give you an hourly rate. Some shops charge you the time spec for the job and if they get it done quicker, they get more profit, and if they take longer, they eat that profit. Most shops charge you a flat hourly fee and will only give you an estimate on the amount of time.
The parts would run probably $100-$150 for all the gaskets, seals, coolant, oil, etc that it will take. The head would probably be anywhere from about $200 used to $1000 new. I really have no idea -- that's just a shot in the dark. While they're in there, you outta have them replace the timing chain, tensioners and guides, if they haven't been replaced already. Cheap insurance against something failing or weakening somewhere down the road.
thanks.. that sounds in line to what I was expecting. They are giong to replace all of that extra stuff you mention and work on the heads also.. not just the gasket so it was fairly in line with what I expected.
clean out the radiator and replace all coolant hoses while you are at it. the failed head is generally a symptom of something else. ensure proper torque of head bolts, replace water pump (which you did), replace thermostat (which you did), definitely purge the radiator, and replace hoses. Use a quality head gasket and make sure the block and head a crystal clean before bolting it up. Check for head warpage or it will happen again.
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changing the compression ratio by shaving the head might actually improve performance (not much since not that much will be taken off). Yet every little helps with these under powered trucks. If head work is needed consider investigating valve seal replacement, etc. while the head in off and the work can easily be done.
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Your gauge could be slightly inaccurate. Some shops have a non contact thermometer. Point at where you want a temperature reading and pull the trigger and it will tell you how hot parts of the engine are getting. See if you can find a shop with one of those and have them beam your thermostat housing to verify the temperature rating of your thermostat with the gauge in the truck.
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