Engine Tapping/low Coolant...

RATCHETS · October 1, 2008

I have read that the intake manifold gasket will leak and let coolant get into the lifter valley on GM engines. I just want to confirm that the 4.3L(non Vortec) in my 2001 GMC Sierra is subject to this problem. I have a tapping noise that started about a week ago and only tapped on cold starts, now it is consistant. I have only driven the truck maybe a mile with it tapping, and now it is just sitting. I'm hoping to replace the gasket(with a Felpro) and soak the lifter valley with oil. This will be my first time working on a GM engine, and I'm unsre how difficult it would be to get to the lifters to clean them/ replace them. Any advice would be greatly appretiated.

RATCHETS · October 2, 2008

Schmids5.3l · October 2, 2008

I've never worked on a 4.3, but I'd imagine getting the heads off wouldn't be too bad. I'm sure someone will chime in with some info. If you've done some extensive work on any type of engine, their all the same

Edit: A weekend should give you plenty of time to get this done, starting on Friday after work or something. Be sure to get new head gaskets and bolts.

RATCHETS · October 2, 2008

Well, actually I believe you just need to remove the intake manifold to get to the lifter valley. And from there you need to remove the rocker arms and lifter retainers. But I'm not sure how difficult that would be.

My main concern is if the tapping problem is common with the 4.3L that is in my truck. I'm planning on changing the gasket this evening, or at least tearing it all the way down. I just don't want to do all this work and have the engine still tapping when I put it back together.

Thanks for the reply!

EDITL: I have never gone into the internals of a head or block before. I am confident in myself enough to do it though. I just try to avoid it if at all possible

RATCHETS · October 3, 2008

I was told it wasn't a Vortec engine, but it is.

I have started disassembling the intake mani and I am just about finished. I will post up what my conclusion is when I'm done.

Zembonez · October 3, 2008

Sounds like your diagnosis is right on. You should be able to pull the intake, clean out the valley, oil it back up, and keep on trucking. The only major problems I've seen as a result of leaking intakes came from people driving them long after they start leaking.

RATCHETS · October 3, 2008

Thanks Zem. I'm about to go back at it. I just need to disconnect the fuel lines and pull the ac and power steering pumps forward and pull her off. Hopefully it doesn't look to terrible under there. I'll post up when I'm done.

RATCHETS · October 6, 2008

Ok, so the engine tapping is gone! I poured about a quart or so over the lifters while I had the intake off and used an engine treatment when i filled the oil back up. It tapped at first but is now gone and hasnt returned. But I do have low oil pressure, which I had before. Now its time to try and fix that. Thanks for the advice guys.

RATCHETS · October 7, 2008

Ok, well I guess I spoke too soon because the tapping is back. I'm just assuming it''s the lifters, although I'm pretty sure since when I changed the intake gasket it temporaily fixed it. My oil gauge dropped down to zero today going down the highway just before I got to work today. It wasn't tapping then, or making any noises really. Even when I got to work i let it idle and it still wasn't making any noise. Maybe its a faulty gauge.

Since I changed the intake gasket, and switched to 5w-30 oil, the oil pressure will to zero at idle. Before I changed the gasket, and when I was running 10w-30, it was running 20-25psi while cruising down the highway, and down to 5-10 when idling. This is all with the engine at normal operating temp.

When I started it for lunch the tapping was back. I bought some engine flush, and then I'm dropping the pan and cleaning the oil pickup. If this don't fix it I'll start leaning towards a new motor/rebuild.

2000DV4.8 · October 7, 2008

If this don't fix it I'll start leaning towards a new motor/rebuild.

6.0!

Zembonez · October 7, 2008

That really sucks. Was there any sign of leaking when you pulled the intake?

Maybe pulling the pan and checking the screen will prove successful. It could be sludged up from the antifreeze contamination maybe?

Let us know what happens.

RATCHETS · October 7, 2008

Well the gasket broke into pieces when I pulled the intake off. I'm not 100% sure it was leaking internally, but you could see where it was leaking at the front of the motor. I will definently post up after I drop the pan.

Will a 6.0, or even a 5.3, bolt to the 2wd transmission and engine bay of my 4.3L 1500?