Question about Dometic Rooftop RV Air Conditioner

1 Answer

Valve noise on start-up

What causes a valve tap noise upon start-up of a cold engine--Chevy 7.4 liter Vortec?

Posted by Chas T on

Ad

1 Answer

Anonymous

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that got 5 achievements.

    Novelist:

    An expert who has written 50 answers of more than 400 characters.

    Governor:

    An expert whose answer got voted for 20 times.

  • Expert
  • 142 Answers

Sticky lifters... I had a similar problem on my chevy 350. One quart of Marvel Mystery oil took care of the problem (2 weeks after use).

if that doesn't help, perhaps try some slick-50. The object is to make the lifters free themselves a bit.

Good luck.

Posted on Apr 16, 2008

Ad

Add Your Answer

×

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

0helpful
1answer

My 04 impala 3.8 has valve chatter only at start up why?

This type of noise is usually caused by malfunctioning valve lifters or an exhaust manifold leak. If the noise lasts for more than a minute and completely disappears or dimishes after the engine is warm, the most likely cause is an exhaust manifold leak. If the noise only lasts for a few seconds, the most likely cause is a valve lifter malfunction. You should start your diagnosis with a visual inspection of the exhaust system. Inspect the exhaust manifolds for leaking gaskets or cracks. Black soot marks where the manifold mates to the cylinder head are key indicators of an exhaust manifold gasket leak. Inspect for broken exhaust manifold bolts. Inspect the gasket area where the manifold bolts to the exhaust pipe. Small exhaust leaks can often self seal once the metal engine parts are heated and expanded.
If there are no signs of an exhaust leak and the noise dissipates a few seconds after starting the vehicle, you should suspect an oil control or valve lifter malfunction. Hydraulic valve lifters use the engines oil pressure to expand the lifter which provides a zero valve lash clearance. This prevents the valves from tapping. When the engine is shut off, a valve and spring in the lifter keep it expanded and retain the oil within the lifter. If the valve or spring allows the oil to drain from the lifter, it will collapse. Upon start up, the lifter will take a few moments to "pump up" and expand as the oil pressure builds in the engine. During this time, the valves may tap since there is clearance between the rocker arm and lifter..

FOR MORE DETAILED HELP CLICK THE LINK BELOW:

https://carrepairworld.blogspot.com/2021/06/car-valve-chatter-only-at-startup.html

THIS WILL HELP THANKS.
0helpful
1answer

Engine got a knocking cold start, silint when hot

It has developed a clicking engine noise on a cold start. After the car has warmed up, the sound goes away. ... Clicking or a sharp tapping from the valve cover on top of the engine would point to a valve train noise. A dull tapping or slapping sound from the side of the engine block would point more toward piston slap.4 Nov 2011

Cold-start engine clicking is a nuisance, not a disaster - StarTribune.com


0helpful
2answers

My engine has intermittent lifter rattling what could be the problem

Chevy Vortec lifter & valve tap how to repair it - YouTube

? 10:08
https://www.youtube.com/watch?v=KPAMIeeY-q8
May 22, 2012 - Uploaded by AdirondackNY
this video has info on how to fix a severe valve tap or sticky lifterusing 1 quart of ... Chevy 5.3 liter lifter noise and motor flush solution How to ...

4.3 engine knock lifter or bearing? - YouTube

? 1:22
https://www.youtube.com/watch?v=oSbyAbS6e2c
May 27, 2010 - Uploaded by jerjer0241
any idea weather its a rod bearing or a lifter or even summin else? the service engine light is on because i have the air intake off. Just did an oil change ... ... Up next. Engine Knocking or Ticking?!? This Could Be Your "FIX" ...

Ticking Noise From Valve Lash Adjusters Due to Infrequent ...

repairpal.com > Problems > Mazda > Mazda6


1helpful
1answer

I have a 1998 chevy 1500 with a 4.3 liter engine,after it sits overnight it takes a while to start. After it is warm it starts fine and runs good,it happens after its cooled down

I would start by checking fuel pressure via the schrader valve on the fuel line (near the rear of the intake manifold). The vortec engines needed considerably higher fuel pressure than most to start cold, and it is quite common for a weak fuel pump to cause a cold only no start condition with that engine. You should see around 50-60 psi with the key on / engine off for about 3 seconds. Also, if the pressure drops very quickly after a few seconds, the fuel pressure regulator could be to blame.
0helpful
1answer

Lost compression and now there is a loud knocking noise in my 454 vortec engine

Bent valves would be number one cause. Check the timing. If you lost time, your valves are tapping the pistons causing the knock. When the valves tap the pistons they bend and don't close all the way, so the cylinders cant make compression.
1helpful
1answer

How do i adjust valves on a 4.3 vortec tbi motor

The 4.3 liter vortex uses a hydraulic lifter. There is no valve adjustment. If you hear a lifter tick than there is either a bad lifter or something broken in the valve train. Something yo can try for a sticky lifter is add 1/2 a can of seafoam motor tune the oil. Start the engine and let it run until the noise goes away. Then change the oil. If the noise doesn't go away than you have bigger issues. I have yet for the seafoam to not fix a sticky lifter especial in the 4.3 liter which we see quite often.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

3helpful
2answers

Lifter

It could be lifters but its more likely that your not getting oil to the top right away. Probably plugged oil passages in the cylinder head. Remove the valve covers and clean it out. Change your oil and see if it helps. The damage may alreay be done though
1helpful
1answer

I have a 96 chevy blazer with a 4.3 vortec rough

Do a compression test on all of your cylinders when it is cold. Backfiring is a sign of a worn valve seat allowing mixed fuel and air (lit by spark) to be forced back into the intake. You will probably see compression loss on one or more cylinders.

Also... there is a chance that the EGR valve is not totally seated when the engine is cold with just a small blow by. The EGR valve seats coke up over time with black gunk.
5helpful
2answers

Replacing pcv valve on 2002 Chevy Silverado 2500 HD Vortec 6 Liter engine

driver side valve cover in the back of the cover. if it even has one, sometimes the cover has been replaced with a later style that uses a baffle instead of a pcv
0helpful
1answer

2001 Chevy Metro

Check Utube for lifter tap, valve tap, and rod bearing noise. If you pull each spark plug one at a time, plugging it back in after each one, the tapping will go away if it's a rod bearing. At any rate, on your next oil change add some valve-medic or similar additive for valve noise. Make sure you follow direction or you will get massive lifter tap if you pour it into a cold engine.
Not finding what you are looking for?
Dometic Rooftop RV Air Conditioner Logo

255 views

Ask a Question

Usually answered in minutes!

Top Dometic Heating & Cooling Experts

Dan Webster
Dan Webster

Level 3 Expert

8221 Answers

Jay Finke
Jay Finke

Level 3 Expert

1391 Answers

Ronny Bennett Sr.
Ronny Bennett Sr.

Level 3 Expert

6929 Answers

Are you a Dometic Heating and Cooling Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...