Looking for some help diagnosing a issue on a 5 month old built 5.3 liter. I have not took it apart yet but the problem is when it's cold it will back fire once and a great while(but only when it's cold). It has some white smoke that comes out of the exhaust when running, not alot and it often seems like it is running hot only when running at idle but smells sweet like coolant but I do not see any leaks. Just wondering if it is one of the 3 below. Thoughts?
- leaking intake gasket
- leaking head gasket (oil looks normal)
- or a cracked head.( heads are about 5 months old. and were properly torqued down.)

 

If exhaust smells like antifreeze, it's either a bad head gasket or cracked head.
Which heads are they? If they are 706, see if they are Castech heads.
They have a small battery-shaped symbol in the rocker area. They are known for cracking.

 

They are Trick Flow Gen X heads. Yeah that's what I was kinda thinking. Just hope it's not a cracked head. Thanks for the feedback, much appreciated.

 

Go rent a block test kit at Autozone look on YouTube and see if you have exhaust gasses in your cooling system, it’s a simple test and will reveal plenty, Look at your motor oil as well, jack your car up, dump the oil ( cold ) into a clean drain pan and have a good look at it, see if there is water based contaminates in it, you can reuse it but you’re most likely going to be draining it anyway. Does you intake gasket have coolant running through it? Probably not. Backfire might be related to small exhaust leak somewhere and most likely to show up when your engine is cold, Running excessively hot is a sign air pockets in your cooling system or poor coolant circulation. Air pockets ARE introduced through a bad head gasket, just sayin. Good luck

 

64post, thanks for the insight. I am hoping that's all it is. I will do that if it is in fact just a head gasket and since I will have it tore apart. Would you recommend replacing the lifters since I am already going to be in there even though they dont give any hint of issues at the moment? Again thank you for the feedback!

 

Yes, if can afford it in your budget and your lifters are original equipment, replace them. Things to think about when you tear it apart, are gasket surfaces truly flat, use a higher quality straight edge to see if your deck surfaces are true, use the straight edge both laterally and horizontally with a light behind it looking for low spots, same with heads, don’t reuse your head bolts if they’re TTY style, get new ones, make sure your steam vent tubes are on and functional, proper torque sequence and steps are really important, don’t deviate from the plan but most of all don’t reassemble it if you have doubts about the surfaces or you may be doing all over again. Make sur your cooling system is filled properly, take a heater hose off if u have to while filling it to make absolutely sure there’s no trapped air, or use a high level fill funnel ( $25) they’re great tool to have around.

 

Thank you, yeah I figured it would probably be wise to switch the lifters out since I was already going to be into the motor. Yes I have torque to yield bolts for the heads and will use new ones. Thank you all for your time and feedback.

 

I just bought some gen X 255s. Th a t would be a shame. Do a leakdown test.