KONNMAN

My late father was the orginal owner of this 2003 Express 4.3lt. It has now 97,xxx miles.I lived in NY. Back in August my mother drove the van with a friend for a short ride. During the drive the van didnt have power and the check engine light was flashing. My friend also told me he noticed the temp gauge to rise and he check and there wasn't any coolant. He filled it up and all was fine but still was misfiring. I took the van to a mechanic and he changed the spider injectors and distributor cap, plugs and spark plugs. Van ran perfect no chokes, hiccups. Now I currently have a code thats 0420. Catalyst needs to be changed. I drove the van from NY to CA in October. Ran perfect, 17.89 MPG. 2,998 miles to be exact. Was happy with the drive. Once I came to CA (I always used regular 5w-30) my unlce in CA took my van and put full synthetic oil. From October until 4 days ago havent had any issues execpt that that Cat code that was always there. The other day I started the van and it started ticking not crazy loud, 40 seconds later it went away. As I was driving I noticed my temp gauge rise. I pulled over right away and noticed no coolant. I filled it up and temp gauge went to normal. Where is this coolant going? And what is this ticking noise?

lunghd

Check for coolant in the oil. GM had, um, "issues" with bad intake manifold gaskets...

oldchevy

The water pump is another common place for leaks. Mine was leaking through the weep holes. It could be a very slow leak which could take a week or two before it overheats. Another area is when coolant leaks into the cylinders and gets burned away therefore there are no signs of leaking.

KONNMAN

The engine oil is clean, no signs of antifreeze in there. How do i check for antifreeze in the cyclinders? Also anyone know whats the ticking noise on cold start up?

canucklehead

Missing coolant without a coolant leak can be from combustion getting into the water jacket due to a bad head gasket. The extra pressure forces out the coolant via the cap and the reservoir overflow tube. You can test with block test fluid.
OEM Block tester test fluid 25739 - Read Reviews on OEM #25739

The ticking could be lifter tap. I am not a fan of full synthetic oil, especially in older engines. You could try an engine flush, and then switch to a good high mileage oil. either conventional or semi synthetic. I use Valvoline Maxx Life.

JIMMYDRIVER1

ditto on everything here already mentioned. Grab ahold of the fan when not running and push it back and forth. If there is play replace your water pump. Bad waterpump bearings will make it seep out the weep hole when running. If you smell antifreeze around it when you get out it's leaking under the hood somewhere. If you smell it inside you probably have a leaky heater core. if you have a lifter ticking I'd say you probably have an intake gasket leak. fix the leak and do an engine flush and oil change it will go away.

KONNMAN

Thank you i will try that tomorrow! I did change the intake gasket when I changed the injectors though.

KONNMAN

Update! I did a motor flush changed the oil and also put Valve Medic. Bye bye ticking! So since thats out of the way my next step is check for head gasket leak.

KONNMAN

Update again! I found a small coolant leak in the lower radiator hose. Changed hose. Hoping thatll be it.

1k miles later my ticking came back!! Why?

Twscarp

Could be some of the residual synthetic oil that was left in the engine after you changed back to mineral oil, is still making the lifter sloppy. I would consider changing the oil and filter at least once, or probably twice at 1000 mile intervals, before attempting anything drastic.