Engine break in problem

[DaveG]

Well, finally got my new Dunerunner running, and was having a great time breaking in the engine this afternoon. After about 15 minutes of the car running great, it just quit on me. I checked and still had fuel left in the tank. I started it again and the revs were all over the place. Also, I noticed fuel coming out where the exhaust attaches to the engine, and it had made a mess all over the back of the car and rear suspension. There wasn't a bunch running out the pipe, just between the housing and engine. I could also feel air shooting out from this location, just about as much as it does from the pipe itself.


I took the exhaust off the car and found that the gasket to the exhaust had pretty munch burned though, and it's obvious that it didn't have a very good seal to the engine. The car will start and idle, but at various times the idle jumps up and down and regardless of tuning, after applying enough throttle to get the car moving, it dies.


So my question is, is this all related to the exhaust meaning if I replace it, this should take care of the issue or does it sound like there is something more serious going on with the engine?

 

[DaveG]

Tried running it again and now I have oil/fuel running down from the top of the engine. Wondering if I have a blown head gasket...

 

[rroberson7805]

From the very top where spark plug is? The gasket is a couple inches down below the heat fins right? I'm still new myself but trying to help u somewhat. Mine won't crank and I'm trying to get help also but nothing yet, lol.

 

[DaveG]

From the very top where spark plug is? The gasket is a couple inches down below the heat fins right? I'm still new myself but trying to help u somewhat. Mine won't crank and I'm trying to get help also but nothing yet, lol.

Correct about the placement, I'm an idiot. I believe the oil/gas blew up to the fins from the area of the blown seal of the exhaust. I'm going to pick up another to see if this fixes the problem. If so, time to buy a better exhaust.

Any luck on getting yours started? I was having problems as well but figured it out. I flooded my engine last weekend. After getting the extra gas out, this is how I started it yesterday.

3 presses on the bulb to get the fuel going. Close the choke, two pulls on the starter. Open the choke, and by the 2nd pull, it was up and running like a champ.

 

[rroberson7805]

I'm thinking (and hoping ) mine is just flooded also. I flooded it once and this happened when I first got it. I will try that. And what exhaust you have? If not a jetpro I highly recommend it, worth every penny.

 

[ROCKHEART]

The "air shooting out from this location" that you describe is probably the air from the flywheel being directed over the cooling head fins so there's no worries there. Head gaskets are known to blow on the 2 bolt heads, and if it has it should be quite visable.

You can see the head gasket between the head and crank case, and if it's blown you'll see a tear/ piece missing surrounded by a black oily residue. Though as your exhaust gaskets gone too I bet the oily residue is everywhere lol.

May be worth checking your head bolts and carb bolts are nice n tight just to make sure.

 

[rroberson7805]

Just tried to start mine again with 3 pushes on bulb, 2 chokes, then regular pulls and still absolutely nothing.

 

[rroberson7805]

Smell gas means it's flooded?

 

[DaveG]

The "air shooting out from this location" that you describe is probably the air from the flywheel being directed over the cooling head fins so there's no worries there. Head gaskets are known to blow on the 2 bolt heads, and if it has it should be quite visable. You can see the head gasket between the head and crank case, and if it's blown you'll see a tear/ piece missing surrounded by a black oily residue. Though as your exhaust gaskets gone too I bet the oily residue is everywhere lol.

May be worth checking your head bolts and carb bolts are nice n tight just to make sure.

Thanks for the info!

Pretty sure my dunerunner is the 4 bolt version, but I do not see anything wrong with the gasket just by looking. All of the residue that I can see is coming from the exhaust gasket, and yes, it's everywhere. LOL

I'll make sure to check the head bolts and carb bolts tomorrow.

 

[DaveG]

Smell gas means it's flooded?

The smell of gas on mine was quite strong when it was flooded. The biggest clue however was the spark plug was soaked. I just took it out and let it dry. Also turned the dunerunner upside down and pulled 8-10 times until all of the excess fuel had come out.

 

[RampageHopUps]

You have to hear the POP before you turn off the choke.

 

[rroberson7805]

Great info. Thank you and will try that next.

 

[Ice_2k]

@DaveG You said "the revs were all over the place", did you mean the engine revved by itself? Did it by any chance have a higher pitch? If it did, you probably need to vent the tank.

 

[DaveG]

@DaveG You said "the revs were all over the place", did you mean the engine revved by itself? Did it by any chance have a higher pitch? If it did, you probably need to vent the tank.

Yep. The engine RPM's rev on their own, and the engine will go to a higher pitch for a few seconds, and then drop back down to idle. It will get up to the point of trying to take off on it's own, and then back to idle. I tried loosening the cap to see if it made a difference but unfortunately it didn't.

This problem hasn't gone away since it cropped up. Even allowing the car to sit overnight, and starting it again this morning showed the same problem.

 

[Ice_2k]

If it didn't get better by loosening the cap, it might be an air leak... I never tried this myself but I saw other people here recommending to spray WD-40 on the carb and the surrounding areas and, if the rpm's go back to normal, it's definetely an air leak somewhere.

 

[DaveG]

If it didn't get better by loosening the cap, it might be an air leak... I never tried this myself but I saw other people here recommending to spray WD-40 on the carb and the surrounding areas and, if the rpm's go back to normal, it's definetely an air leak somewhere.

It's worth looking into for sure. I'm starting with replacing the exhaust gasket and going from there. It might be just a big coincidence, but the timing of the engine problems along with the failure of the exhaust gasket is interesting for sure. The entire run before the issue I would stop the car after 2 passes and look at things. I never noticed any oil/gas on the rear suspension/rear of the car until the car quit on me. That's when I followed the trail and noticed oil/gas coming through one of the bolts to the rear exhaust, as well as blowing up to the top of the engine and basically everywhere around the exhaust canister.

 

[Ice_2k]

My exhaust gasket also got pretty much melted rather fast, you definetely need to upgrade that

 

[DaveG]

My exhaust gasket also got pretty much melted rather fast, you definetely need to upgrade that

Could a bad exhaust gasket upset the engine performance like I'm experiencing?

 

[Ice_2k]

I don't think so, to be honest

 

[DaveG]

I don't think so, to be honest

I figured as much. I'll replace the gasket anyways and see what happens. After that, I'll look at the cylinder gasket and if that's not it, I probably won't be spending too much more time on it. I have an extra spark plug that I'll test, but I'm not tearing a brand new motor apart to find the problem.

Unfortunate, but at least I got 15 good minutes out of a new car.