My 3.4L 4Runner started doing something strange lately! When leaving from a stopped position, like a stop light, the truck seems to hesitate?? Also, when I hit approx. 70kph, the truck starts to vibrate? I tried adding some gas antifreeze, thinking I may have had water in my gas, that didn't work. When checking under the hood with the motor running, I noticed a small amount of white smoke coming from the back of the motor near the fire wall??? The engine light came on, and intermitently flashes sometimes?? The hesitation does not occur everytime I drive it. In fact, today I took the truck out twice, and it only did it once. The light stayed iluminated, but the hesitation was not present???

Anyone ever had this problem??

 

Head gasket?


Andreas

 

When did you change your spark plugs last? Same thing was happening to me, except the smoke, and I found out that my plugs were bad (no spark on #3). Bought all new ones with new wires and it was fine. And yes it seemed like my CEL would come on when I go up any hill or when I would make a quick acceleration. If it isn't the plugs, I don't really know, maybe a vacuum leak?

 

Well, it may be too soon to tell, but I may have figured it out! I decided to take a look at my Coolant level in my rad, and well.....it was dry! I dumped in an entire jug of Coolant into the rad and reservoir, then disconnected my negative cable from the battery. Once I reconnected the battery, the light did not come back on, and the truck ran great today!

I hope it's not too early to say, but it seems as though my problem may be resolved! Does anybody here think that this should have fixed my problem? Is it too good to be true??

 

Sounds to me that your problems are far from over. You need to fnd out where that coolant went. Check your oil and your radiator. Make sure your fluids aren't mixing into strawberry or chocolate milkshakes.

 

Check transmission fluid too. Unless there's a puddle under your truck...that coolant is somewhere it isn't supposed to be.

 

clean the MAF too

but also find out where the coolant is going.

 

I checked the oil and the transmission fluid the same day I added the coolant, and they looked normal....The rad was drastically low, but no fluid on the ground, like I said, the oil and tranny fluid was good?? Could it have just evaporated? I don't usually look at the coolant level.......dumb I know....but I figured my temp gauge would tell me if the truck was getting hot.....The rig is still running great, and no engine light present???

 

I guess it's possible the previous owner didn't refill the coolant properly. How long have you had the truck? Either way, low coolant wouldn't do what you've described in your original post. I'd drop your transmission pan and get a good look at the trans fluid.

 

Worst case scenario, which actually crossed my mind as being probable from your description would be a blown head gasket. White smoke (from tail pipe, or if you have an exhaust leak) means you have water/coolant getting into the cylinder. Since your coolant is low, it sounds like the gasket might have a hole that is allowing the water to enter the cylinder.

Why not pull the CEL? Get a reading and see what it tells you. I would personally watch that coolant level like a hawk.

The vibration at high speeds is probably something very simple, like rotating and balancing your tires or lubing your driveshaft.

 

So I got the truck checked out by a diesel mechanic friend of mine. He did a pressure test on the coolant system, and found that the truck was losing pressure. He looked at a few different areas, almost gave up on looking, and then found my problem. We ended up finding a coolant line under the truck, which feeds the rear heater, that was all corroded. He replaced the line with some small rubber hose, threw on a few hose clamps, and sent me on my way!

It's crazy, because the line was barely dripping, but once he started moving it around......it was squirting all over the place! He sent me on my way, with some extra coolant in hand, and told me to keep an eye on the level.....if I'm still losing fluid, then I probably have another leak.

Anyways, thanks for the replies, and I'll keep you guys posted if there are any changes!

 

Still, like Qyota said, low coolant wouldn't make your truck run so crappy. Good luck, but it sounds like there's something more to this.

 

would a low coolant level trick the coolant temp sensor some how n make it run odd.

 

my truck ran like that when there were air pockets in the cooling system

 

I was kinda thinking the same thing........