low idle (500ish) check engine light on

[jacksonh18]

the code at Autozone was P0174

I just finished putting new heads, pushrods, rocker arms, plugs, plug wires, Gibbs break in oil, thermostat, radiator fan in.

Occasionally the oil pressure gauge is going crazy and I just replaced the oil pressure gauge switch (sending unit). I am now installing a real oil pressure gauge.

I purchased some mass air flow meter cleaner and I'm about to clean that.

What order would you go thru checking these things? Is there a way to test a mass air flow meter? (it's over a hundred for that part)

 

[rb142]

Funny how that Autozone diagnosis completely ignores the absolutely most common cause of that code -- a vacuum leak.

Often there is a leak in the inlet tube downstream of the MAF. But that would normally set the code for both banks. If you really only have the code for one bank, it could be something like a manifold gasket leak.

Obviously there are a lot of other things it could be as well. I'd sort out that oil pressure question first if I were you.

 

[koda2000]

BTW a low idle can be the reason your oil pressure gauge is going nuts. the lower the idle the less oil pressure you have. if it gets low enough the gauge will go to max LOW as it's not really a gauge. it's more like an idiot light with a needle. if you have adequate oil pressure the gauge sits in the middle. if not it drops to LOW. the oil pressure "sender" is really a oil pressure switch.

 

[jacksonh18]

There is oil in my coolant before replacing both heads I had coolant in my oil. I suppose I have to buy new gaskets and start over. Anyone have any suggestions? I thought I did everything right....

 

[lobo411]

There is oil in my coolant before replacing both heads I had coolant in my oil. I suppose I have to buy new gaskets and start over. Anyone have any suggestions? I thought I did everything right....

Check the timing chain cover gasket for signs of leakage. There's a coolant passage that runs through the timing chain cover and while mine leaked externally, yours could be leaking internally.

Also, is there coolant in your oil?

 

[jacksonh18]

I checked the compression

Does this rule out the head gasket?

 

[jacksonh18]

my transmission fluid is bone dry I suppose it is probably trans fluid in my oil..... What causes this and how can I fix it?

 

[koda2000]

my transmission fluid is bone dry I suppose it is probably trans fluid in my oil..... What causes this and how can I fix it?

i don't see any way trans fluid can get into your engine oil. the only thing that can happen is to have trans fluid and coolant mix if the radiator has an internal leak.

your compression numbers are w/in 10% of each other (although i think a bit low). did you check them with the throttle plate open? i don't think this indicates any gross head gasket leaks, but it doesn't guaranty you don't have a small head gasket leak either. did you replace the head bolts when you re-installed the heads? was the engine overheated at any time?

 

[jacksonh18]

oops, typo... Its in my coolant. It wasn't bone dry, but a couple quarts low and the trans fluid is in my coolant reservoir.

 

[rb142]

Then the trans fluid is getting into the coolant in the radiator. You need a new radiator. Good chance you also have coolant in your transmission fluid, so it would be a good idea to drain out as much of that as possible and replace.

That does not explain the P0174 or the oil gauge fluctuations. You need to keep looking for those.

 

[jacksonh18]

Then the trans fluid is getting into the coolant in the radiator. You need a new radiator. Good chance you also have coolant in your transmission fluid, so it would be a good idea to drain out as much of that as possible and replace.

That does not explain the P0174 or the oil gauge fluctuations. You need to keep looking for those.

Sounds like a plan... The engine light was a leak from the EGR valve. hopefully I can fix it, but I don't think it is hurting anything. I think the oil pressure was probably from the low idle. I still need to install the real oil pressure gauge I bought.

This has turned into the biggest pain in the ass.....

 

[jacksonh18]

i don't see any way trans fluid can get into your engine oil. the only thing that can happen is to have trans fluid and coolant mix if the radiator has an internal leak.

your compression numbers are w/in 10% of each other (although i think a bit low). did you check them with the throttle plate open? i don't think this indicates any gross head gasket leaks, but it doesn't guaranty you don't have a small head gasket leak either. did you replace the head bolts when you re-installed the heads? was the engine overheated at any time?

The engine has 120K on it. Do you mean did I press the gas while turning the engine over when I tested the compression? (No I didn't) Would that make a big difference? I replaced the bolts and torqued them to specs.

 

[rb142]

An EGR valve leak shouldn't be too hard to fix. That is probably the source of your lean code, and thus your low idle, and thus your low oil pressure. You might be able to fix them all in one shot.

Yes, having the throttle plate open during the compression test will make a big difference.

 

[koda2000]

The engine has 120K on it. Do you mean did I press the gas while turning the engine over when I tested the compression? (No I didn't) Would that make a big difference? I replaced the bolts and torqued them to specs.

opening the throttle plate during the test would allow more air into the cylinders and give a higher compression number. as you didn't do that, it's probably why your compression numbers are a bit low. a compression test is good for assessing the general heath of an engine (rings, valves) it's not great at testing for a blown head gasket unless it's a pretty major gasket break. a leak-down test while checking for air bubbles in the radiator is a better test.