KONNMAN

My friend told me the same thing. I will be changing the oil in few weeks.

KONNMAN

Hopefully someone can help here again. I drove the van about 500 miles round trip and engine started tapping again. After that the oil pressure gauge was rising to 80 and then back down to 60. I put the van in drive and it would go straight to 80psi. After driving for 10-15 min pressure goes to normal 35-45psi and ticking stops. Any ideas? Can it be the oil pressure sensor? Its so aggrivating since this van doesnt even have 100k!

Twscarp

What kind of oil are you using? I would change the oil and filter like two times after the synthetic. I would use straight (5w-30) mineral oil no synthetic or semi. Try a new oil pressure sender, their cheap. Not sure if you can get to it without removing the doghouse, if not, remove the passenger seat to totally get the doghouse out of the way. Did you ever get to the bottom of the overheating and loss of coolant? For some reason one of your lifters (they are hydraulic) is leaking down, but regains the pressure after 10-15 minutes. Could be wear of an internal part of the lifter, or sludge is blocking a passage or oil hole, or varnish has accumulated on the moving parts making it move sluggishly. Has the oil been changed at regular intervals? I would keep trying to find a solution because the noise means some extra wear and potential damage is happening.

canucklehead

What oil filter and oil are you using? Gm recommends semi synthetic blend oil that is dexos rated. As for filter, no fram or other cheap ones like quaker state. Try a performance filter, like Mobil or Napa Gold.
If you have a sticking valve, there is nothing you can do without pulling the heads. Shops I know have tried filling an engine with solvent and letting it sit for a few days, and flush, still ticks. Sometimes mechanical issues need mechanical repair.
Have you tested the coolant with block test fluid? have you ruled out head gasket issues?

Twscarp

All good points canuklehead, fluid changes may not solve the problem. Konnman's van is it 2003 4.3, that motor still used straight mineral oil, as does my 2008 Express 1500 4.3, dexos1 came out in 2011, as the standard GM oil. Dexos1 is a semi synthetic, I see now that there is a dexos1 Gen2, that is apparently a full synthetic. I keep thinking back when the uncle in California changed the oil, an engine that had 95,000 Miles with mineral oil, then was changed to a full synthetic (assuming full synthetic), don't think that was the best move to make. Changing the oil and filter several times, is relatively cheap and painless, I think if it was my van I would do that, but no guarantees. On my 1992 G 20 cargo van 4.3, I think the van had about 250,000 miles, it was a very cold winter morning I think in the teens, went out started it, came back in the house, about 10 minutes later I'm hearing all this racket out there, bang bang bang bang bang, ran out and shut it off and it was a lifter but it was loud I mean really loud. I took another car to work and called my friend the mechanic who lived almost next-door this was 20 years ago and I don't remember exactly what he did. I remember he did put in some valve medic and changed the oil and filter a couple times but it fixed it. That van ended up with 316,000 miles and was still running fine.

Twscarp

You might try this for another answer. Most Saturday mornings there is a radio show out of Detroit, “The Car Show”, where the hosts take automotive problem questions, and try to figure it out. They are very good, you call in with your question, put on hold, then when your turn comes up you describe your issues to the guys and they diagnose the problem on the air. You have several issues, the oil change, the overheat/coolant, and the oil pressure thing. I would limit your questions to the oil change, the lifter noise, get their opinion. If you do this, try to record the conversation. Google it to get the number, they are live today at 10:00am to 12:00 EST. Highly recommended, informative radio show, you could listen online today to get an idea how it works, or call today.

KONNMAN

Thanks guys. The whole coolant level I haven’t looked into it yet because I only added very little in the reservoir tank to keep levels up, yes I understand it shouldn’t be losing coolant! I feel its not losing enough to make it a concern at the moment. This week I will get the block tester for coolant. My uncle had changed the oil to synthetic when I first came to California and literally right after 2500 miles i started getting the valves tapping. I changed the oil to the one you recommended canucklehead. Valvoline MAXXLIFE. With Valvemedic. And with oil filter I went with Wix. And again after 2500 miles hit again the valves started tapping again, with the oil pressure gauge going from 35-80psi then after 15min the tapping will go away and the pressure with idle at 35-45psi. I was thinking of changing the pressure sensor with seems pretty easy to do.

Twscarp

OK guys I don't want to keep beating a dead horse, but it seems to me the lifter noise was the result of changing the type of oil, from mineral (organic) to synthetic (man made chemical). For 95,000 miles the owner used regular mineral oil, then in California it was changed to full synthetic oil. This is a sentence in Konnman's 1st post of this thread: "Once I came to CA (I always used regular 5w-30) my unlce in CA took my van and put full synthetic oil". Now I may be wrong, I'm not a professional mechanic, but to me that is a drastic change. That is why I kept stressing changing out the synthetic oil with mineral oil, with the filters of course. To the best of my knowledge GM started using the semi synthetic Dexos1 in 2011. So your 2003 4.3 was always a mineral oil motor. We still don't know the exact oil you used. "Full Synthetic High Mileage With Maxlife Technology" is one of the Valvoline products with Maxlife in the name but is full synthetic, while Maxlife (High Milage) is semi synthetic.The Maxlife oil is a semi synthetic, so you drained out a full synthetic from California, and replaced it with a semi synthetic. If that in fact was the oil you used. My idea was to try and remove as much of the synthetic oil as possible, with repeated oil and filter changes, and replace it with a mineral oil that it had for 95,000 miles. So doing what I suggested hasn't been done, and that's fine, it may or may not work, but even at a GM dealer you can get an oil and filter change probably under $50, I know around here it's like $30, if you didn't want to get under it and do-it-yourself. If it was my van I would spend the $100 - $150 on several mineral (conventional) oil and filter changes, and again it may not resolve the problem, but I would have the peace of mind that I tried something.

https://chevroletforum.com/forum/att...1&d=1491687261

KONNMAN

Thank you. I used the Maxlife High Mileage.

Twscarp

Hi again I spoke with a professional mechanic this morning before church, he said synthetic oils aren't a problem in themselves, it's the powerful cleaners that is in them. That on a older engine the synthetic oils break loose the sludge and gunk, and then those particles are floating around in the engine. He did mention an engine flush, which in my opinion is pretty risky, I wouldn't recommend it. He also said he's had great success with Marvel Mystery Oil. I would probably do the mineral oil changes and filters, plus try adding the Marvel Mystery Oil. Good luck.