1999 Tahoe/Lifter or Exhaust Manifold?

[newtahoeguy87]

Hey guys my recently purchased 99 5.7 Vortec Tahoe has developed a tick on cold starts. I’m hoping someone knows a way I can find out if this is a lifter issue or maybe a exhaust manifold leak. (Or ruling one or both out)

The ticking begins at cold start of engine and stops shortly after running. The duration of ticking seems to directly correlate to how long the truck has been sitting. When sitting for a hour or so the ticking only last 20-30 seconds from start and then goes away. When sitting overnight the ticking lasts 2-3ish minutes.

After fresh oil change the ticking was still the same.

Are there any tests that can be run at home to pinpoint or rule out a lifter vs exhaust manifold leak?

Any help greatly appreciate!

 

[OR VietVet]

If you have a manifold leak you may be able to feel the leak with your hand. It is also recommended that you get a mechanic's stethoscope to help pinpoint the source of noise.

 

[swathdiver]

Seems like a lifter issue to me. Get a long extension or screwdriver and stick one end in your ear and move the other around the engine bay until you pinpoint the noise.

When one of my exhaust manifold gaskets started leaking, it sounded like the motor was going to come apart and did not go away as some do.

 

[wjburken]

Check your manifold bolts and see if one has broken or is loose.

What is your oil pressure like at start-up? Does it come straight up and level off right away or does it build?

Might put a can of Seafoam in your oil, run it for 50 miles or so and change the oil and filter out with fresh synthetic and see what happens.

 

[Joseph Garcia]

I had that same issue on my 97 Yukon for 5 years. Still had the issue when I dropped it off at the junk yard. Was never a problem.

 

[east302]

If you have a manifold leak you may be able to feel the leak with your hand. It is also recommended that you get a mechanic's stethoscope to help pinpoint the source of noise.

I’d agree with the stethoscope approach, it’ll be noticeable when you put it on an exhaust leak.

 

[iamdub]

+1 for the stethoscope. GM vehicles should've come with one in the glove compartment.

 

[Donf]

Just playing the odds most old engines develop lifter noise eventually, especially if they haven't had frequent oil changes. Long term use of synthetic seems to reduce the occurrence as well. Manifold issues are relatively rare.
I like to run a bottle of MMO through my engines once a year , seems to work for me. Seafoam - IMO- is a bit more drastic and I haven't used it on my 99 because it's oil tight now and I would like to keep it that way.

 

[exp500]

A switch to diesel engine oil is also a plus for cleanup in an old engine. 15-40 a good choice for these trucks. If it is an oil burner be aware of cat poisoning. But one oil change interval with 2 filters worthwhile. Almost as good as 1/2 qt of ATF in oil.
When were valves adjusted last? Every 50K miles?

 

[iamdub]

A switch to diesel engine oil is also a plus for cleanup in an old engine. 15-40 a good choice for these trucks. If it is an oil burner be aware of cat poisoning. But one oil change interval with 2 filters worthwhile. Almost as good as 1/2 qt of ATF in oil.
When were valves adjusted last? Every 50K miles?

+1 for diesel engine oil. I run T6 in a 50/50 mix of 15W-40 and 5W-40 for a 10W-40 average. That oil doesn't break down hardly at all in my 5K OCIs.

LS engine doesn't have adjustable valves.

 

[Eman85]

My 1998 has been doing tat for about 12 years now, also has piston slap when it's cold. Runs just fine and just keeps on going. Bought a 99 Yukon and it did it a little. Put some Marvel Mystery oil in it and it doesn't do it any more. Be happy it's a old design SBC, if it was an LS lifter tick is bad news.

 

[CTUBS8732]

Check your manifold bolts and see if one has broken or is loose.

What is your oil pressure like at start-up? Does it come straight up and level off right away or does it build?

Might put a can of Seafoam in your oil, run it for 50 miles or so and change the oil and filter out with fresh synthetic and see what happens.

I did this and had a few loose ones and 2 broken ones. Replaced the ones I could and used a repair clamp on the broken ones.

 

[newtahoeguy87]

Check your manifold bolts and see if one has broken or is loose.

What is your oil pressure like at start-up? Does it come straight up and level off right away or does it build?

Might put a can of Seafoam in your oil, run it for 50 miles or so and change the oil and filter out with fresh synthetic and see what happens.

Hey @wjburken,
Thank you for the sea foam suggestion. After reading the comments and comparing my ticking sound, I was leaning towards a lifter issue over the manifold leaks. I put half a can of sea foam into my oil and ran it for 215 miles (this took about a week). I noticed no real improvement in the ticking sound the entire week but aimed for the 200 mile mark. Yesterday I took it in for an oil change and initially the ticking sound was still present but much softer. Drove about 15 miles and went home.
Woke up this morning and the sound is gone. Truck sat overnight for about 15hours which normally would guarantee the ticking sound for a short period but this time did not. Sound has not returned so far.

Any recommendations on if I should run the other half can of seafoam through the oil to “extra clean” or is there risk of causing damage if I do?

Thanks again to all for the guidance and support. (I purchased a stethoscope as well and just waiting on delivery)

 

[wjburken]

Hey @wjburken,
Thank you for the sea foam suggestion. After reading the comments and comparing my ticking sound, I was leaning towards a lifter issue over the manifold leaks. I put half a can of sea foam into my oil and ran it for 215 miles (this took about a week). I noticed no real improvement in the ticking sound the entire week but aimed for the 200 mile mark. Yesterday I took it in for an oil change and initially the ticking sound was still present but much softer. Drove about 15 miles and went home.
Woke up this morning and the sound is gone. Truck sat overnight for about 15hours which normally would guarantee the ticking sound for a short period but this time did not. Sound has not returned so far.

Any recommendations on if I should run the other half can of seafoam through the oil to “extra clean” or is there risk of causing damage if I do?

Thanks again to all for the guidance and support. (I purchased a stethoscope as well and just waiting on delivery)

Glad to hear things are improving.

I personally wouldn’t put any more Seafoam in again until right before the next oil change. If you went with a quality synthetic oil, that will help as well, and I might go with a reduced oil change interval, and change the oil again after 1000 miles.