jaromgi

I'm going to ask another question that shows how little I know about cars.

Could a ruined head gasket be causing some of my troubles? I just noticed that my coolant is disappearing without a leak that I have been able to find. From the little I know, a bad head gasket could cause the coolant and oil to mix or get burnt to disappear, but would it also cause (or contribute) to the low mpg?

If it is the head gasket, it is something that a person with VERY limited skills could do? I'm willing to put in time, but I don't want to risk permanently damaging the car.

audiofreak97

Disappearing coolant and the like can be a bad head gasket. It's not really hard to change. You could do it in a day. Two if you are taking your time.

The hardest part is taking off the intake/exhaust manifolds, but you don't really need to; it just makes it a bit easier/lighter when lifting off the head.

The most important thing to do, to make the whole thing easier, is do not drop the timing chain! haha Pulling that timing cover off is a PITA.

NismoPick

Signs of a blown head gasket:
-Milky / foamy light brown oil
-Overheating
-White exhaust (will likely smell like coolant).
-Disappearing coolant
Depending on the where the break is & severity:
-Bubbles in coolant
-Rad cap / overflow dumping coolant
-Clean (like "steam cleaned" ) spark plug tips

So... do some digging on those things. Make sure you inspect & compare the plug tips. Also check the head gasket all the way around the motor (you will need a flashlight & mirror for the manifold side) and check for streaks on the block at the head. It could also be a leaky heater core (any smell of coolant in the cabin?).

Lastly, you could always try Bar's Leaks coolant sealer additive... not very good for your cooling system, but will stop leaks.

audiofreak97

I put some in my engine before it went, and I found it in the oil when I pulled the pan could be why it went

jaromgi

- Milky/foamy light brown oil (nope, oil looks clean, at least on the dipstick. I will drain a little from the pan soon and report back)
- Overheating (nope)
- White exhaust (nope)
- Disappearing coolant (yes. I filled the reservoir up two weeks ago and it was 2/3 gone yesterday)
- Bubbles in coolant (will check tomorrow, the car must be running, correct?)
- Rad cap/overflow dumping coolant (no signs of dumping coolant)
- clean spark plug tips (will check soon and report back)

NismoPick

The overflow isn't very accurate to be taking a reading from... the coolant system will fluctuate how much it can contain depending on heat, air, and throttle (water pump is belt driven... so rpm dependent).

You should be checking coolant level at the radiator cap.

jaromgi

Update:

I changed the idle speed from 1300 down to the 700 that is recommended in the FSM, but I am still getting horrendous gas mileage.

I pulled the spark plugs and ended up replacing them. They didn't look too bad, but they had a rough go before I replaced the gas tank and drained the bad gas in the car. I didn't see any oily deposits or other warning signs outlined in the Haynes Manual. I will post a pic of one of the spark plugs I pulled. I've checked the air filter, and it seems to be pretty clean. It was replaced less than 1k miles ago.

From searching the forum, it seems like the next step is to check the ignition timing and see if it is up to factory specs. Maybe I will try cleaning the CHTS and a couple other connections and update again.

Also, I noticed that my oil seems to be leaking. No smoke from the exhaust, but I put 5 quarts in about 1K miles ago, and it is already reading on the low end of the dipstick. I also haven't noticed any oil underneath where I park the car. Any suggestions on where to look?

ThaPimpShrimp

Valve cover gasket is where I had my bad oil leak, and definitely check out the timing! It was what has caused most of the issues my new Z has had.

NismoPick

O2 sensor, AFM, CHTS, timing, and proper tire pressure all affect mpg. I noticed in your vid the other day that the SENOR light is on... I hope your car isn't still running the orig O2 sensor... We will check all that on Saturday. Bring a timing gun if you have one (mine is in Bountiful).

jaromgi

After working at the car at your place, I checked the fluid levels and the overflow was bone dry again. That means I've filled it fully three times in 1000 miles. If it isn't a blown head gasket, I've got to figure out why on earth I'm losing coolant and oil so quickly. Not much I can do until I get back, though.

FricFrac

Did you pressure test the cooling system?

jaromgi

Nope, is that in the FSM or Haynes Manual?

jaromgi

Update: I checked the radiator the other day, and there was a very thin layer of what looked like oil on top. It was sort of orange, and just floating on top of the fluid. However, my spark plugs looked normal, and when I checked the oil dipstick, the oil looked clear. The other day it blew white smoke, but it was only a tiny bit. I'll do a compression test to be sure, but at this point I am leaning towards the idea that I have a small issue with the head gasket.

jaromgi

update again: still only getting around 13 mpg. could this be just because I don't get to drive it very far each day? It is city driving, but even then, it seems like it should get better than 13mpg.

NismoPick

How far is "not very far" ? A mile or two each direction, in the cold, would definitely be around 10-15mpg. Pure freeway driving should average 20-27mpg.

Gasoline motors do need to warm up to operating temp before they become efficient (thus the reason you do emissions / smog test at operating temp).

Did you do a compression check yet? Unless you've got a monster blown head gasket, I'd just keep driving it and keep an eye on the coolant / oil.

jaromgi

whelp, that's what I get for not describing my use well enough. I only live less than 2 miles from work, and I bought the car so I wouldn't have to ride my bike in the rain and snow. Added together, than means that the car is mostly driven under 2 miles in cold weather and slick roads. I knew there would be an efficiency drop, but I guess I didn't realize that it would be THAT much. It is a mistake that anybody could make, right guys? guys?

Not yet, but I will soon.