how to fix... =(

Danteneon · Post by **Danteneon** » Wed Feb 02, 2011 8:56 am

Hydrolock means that water has entered the combustion chamber. Since water will not compress like air will, the rods will bend instead.

Rod knock means that there is play between the rod and the crank. That allows the rod to slap against the crank as it rotates instead of just spinning. Normally caused by flattened rod bearings.

Wrist pin knock is the same as rod knock, just at the piston end of the rod.

Piston slap is when the piston moves for and aft in the cylinder bore instead of sliding straight up and down. Normally caused by the cylinder becoming "egg" shaped from the normal force of the piston to wall load.

thisdieingdream1 · Post by **thisdieingdream1** » Wed Feb 02, 2011 4:19 pm

wow your smart ha thanks man!

now do any of those 3 mess up the cylinder walls?

Danteneon · Post by **Danteneon** » Wed Feb 02, 2011 4:29 pm

In the end, all of them can if the problem is bad enough. Rod knock is the worst of those problems. Wrist pin knock is (IFAIK) unheard of in a Neon. Piston slap is pretty normal in a Neon and has not shown to be a real problem yet (other than being annoying).

And to be honest, even rod knock is kinda uncommon. If oil changes wern't done often enough, or the car was run low on oil for a while, then rod knock could be a possibility. If the rod has enough play in it, then it could lead to the cylinder walls being damaged. Again, this would have to be going on for a while. Our engines can take a lot of abuse.

thisdieingdream1 · Post by **thisdieingdream1** » Wed Feb 02, 2011 4:37 pm

is there a way to determain what it is... like i dk compression tests or such... or is the only way to find out what it is is to listen and take apart

Danteneon · Post by **Danteneon** » Wed Feb 02, 2011 5:09 pm

A compression test will reveal some issues, but not if you have a rod knock. A compression test pressurizes the combustion camber at TDC. If air is escaping where it shouldn't, it will show it. Where the air is going tells the tale...

Intake manifold = intake valves
Exhaust = exhaust valves
Radiator = head gasket
Oil fill cap = rings (could be head gasket as well)

But a test is just that, a test. It is more a tool to point you in a direction of were to look. Want to know how your cylinders look or if the bores are round? Pull the head and see. Need to know if the rod bearings are bad? Drop the pan and check them. You will need to replace the bearings if you pull them out though (don't re-use them).

thisdieingdream1 · Post by **thisdieingdream1** » Wed Feb 02, 2011 5:17 pm

your....reallllly helpfull haha...

i see. cuz i was going to take it up to cumberland valley motors and have then do a check on it to see what that noise is... its 90 dollars but they have like HIGH TECH stuff there...

Danteneon · Post by **Danteneon** » Wed Feb 02, 2011 5:19 pm

$90.00 a hour is pretty standard now for labor.

thisdieingdream1 · Post by **thisdieingdream1** » Wed Feb 02, 2011 5:29 pm

yeah it is....do you think i should get it looked at?

iThane · Post by **iThane** » Wed Feb 02, 2011 11:28 pm

i think (not to be mean or anything) you should just do what most people do with these knocks and just leave it be, or 2.4 swap it lol. my engine for some reason only knocks during the winter, and its only on start up, but i've left it alone and i don't see any difference in mpg or power personally. its just really annoying, but not a mandatory fix. like said before, if you're going to try to fix it, you might as well spend your money on a whole new engine. its going to cost just about the same if not cheaper for a new engine.

OB · Post by OB » Wed Feb 02, 2011 11:39 pm

Danteneon wrote:A compression test will reveal some issues, but not if you have a rod knock. A compression test pressurizes the combustion camber at TDC. If air is escaping where it shouldn't, it will show it. Where the air is going tells the tale...

Technically you're referring to a cylinder leak down test. A compression test is technically just the measurement of the cylinders static compression, for comparison.

Danteneon · Post by **Danteneon** » Thu Feb 03, 2011 8:01 am

Correct. I was eluding to the idea that when adding air to the combustion chamber to test compression, you could then find out where the air is going to see where the problem lies.

I kinda blended them together. Didn't want to overwhelm the OP with too much info at once

thisdieingdream1 · Post by **thisdieingdream1** » Thu Feb 03, 2011 12:06 pm

is there any other types of tests though?

Danteneon · Post by **Danteneon** » Thu Feb 03, 2011 12:35 pm

To address your concern? No. If you want to know for sure what the problem you may have is, the engine needs to be disassembled. There is no good way to look into the engine to check bearing clearances/condition without getting to them. Bore condition can be checked for wear without removing the head (with the right tools), but not to see if it is round.

thisdieingdream1 · Post by **thisdieingdream1** » Thu Feb 03, 2011 1:35 pm

i see i see...

OB · Post by OB » Thu Feb 03, 2011 8:50 pm

Danteneon wrote:Correct. I was eluding to the idea that when adding air to the combustion chamber to test compression, you could then find out where the air is going to see where the problem lies.

I kinda blended them together. Didn't want to overwhelm the OP with too much info at once

Just giving you a bad time

Carry on!

thisdieingdream1 · Post by **thisdieingdream1** » Fri Feb 04, 2011 3:17 pm

why is there blue shit coming out of my battery posts??????

Danteneon · Post by **Danteneon** » Fri Feb 04, 2011 3:20 pm

That would be battery corrosion. Battery could be weak, old, or you may not have a good connection at the terminals.

thisdieingdream1 · Post by **thisdieingdream1** » Fri Feb 04, 2011 3:33 pm

ohhh hmm it didnt start doing it untill i put my 2 amps in... maybe your right... geting another amp for a total of 3 might not be approved by isac newton...

thisdieingdream1 · Post by **thisdieingdream1** » Fri Feb 04, 2011 8:31 pm

what is the average cost to have a crank machined?

Post by **occasional demons** » Fri Feb 04, 2011 9:33 pm

You would need to call the machine shops around your area. Most have a set price for whatever level of repair it may need. Generally from polishing to grinding material off to make it round again. They really can't give you an exact quote, until it is measured, to see what the damage is. But they can give you a best case/worst case price.