2004 Blazer 4.3 liter tapping when cold.......


bandit7862
11-18-2009, 06:19 AM
I am experiencing major lifter tapping when the engine is cold but completely goes away when it is warmed up. I believe I may have caused the problem buy not changing my oil every 3 mo/3000 miles last spring. Could this be an indication of too thick of sludge oil in the bottom of the oil pan? Do I need to remove the oil pan and clean the screen? Any advice would be greatly appreciated.

oneav8or
11-18-2009, 12:27 PM
I've got the same issue. 1999 Blazer 4.3 liter with 123000 miles. Have never gone over the 3000 before oil change and use Valvoline High Milage 5w-30. Was real bad, before last oil change. When it started the heavy tapping I changed the oil right away thinking maybe the oil had just broken down sooner than normal (was at 2 months and 19 days and 1600 miles since the last oil change). Problem went away completely, but now 670 miles and 1 month and 12 days later, it's starting to do it again, not heavy but noticeable for just a couple seconds....not sure what's going on. Last oil change I used a flush treatment, thinking maybe the oil ports where getting clogged. Any one else had this problem and fixed it?

blazes9395
11-18-2009, 11:21 PM
Are you loosing any coolant? Have the intake gaskets ever been changed and/or checked to make sure they are not leaking? Intake gaskets are common problems on these truck and if they start leaking, even a little bit, internally, they can make lifters noisy which could eventually lead to damage. That said, chaning your oil regularly, and making sure you have a good oil fitler, which is very important, especially with externally mounted oil filters, is important to avoid dirty internals.

If your not leaking coolant and believe its just a dirty engine, try gettting some engine oil supplement from a gm dealer and add a bottle in it with you oil(careful not to overfill of course) and see if that helps.

Airjer_
11-19-2009, 01:21 AM
If its for sure a lifter tick get a can of Seafoam Motor Tune. Dump half a can in the oil and run it 5 minutes, 100 miles, or anything in between. Change the oil. See if the problem comes back.

bandit7862
11-20-2009, 05:04 PM
I have also used an engine flush prior to changing the oil where I ran it idling for about five minutes, then drained and replaced the oil and filter. I have done this twice so far but the tapping or ticking noise still comes back but only when it is cold. It is just a nuisance at this point, but I also dont want major engine damage either. I plan on dropping the oil pan soon and look at the build up inside and hopefully there is a screen and maybe it is partially clogged. That would be great to actually find a problem.
I also do think I have a coolant problem but unsure where it could be from. I have changed out my radiator, water pump, hoses and thermostat. I do not have a noticable leak on the ground but it is going somewhere. I do not have coolant inside of my oil because my dipstick doesnt show a milky residue. It could be leaking outside the intake manifold, so I may change them as well. Any other suggestions would be greatly appreciated.

blazes9395
11-20-2009, 05:37 PM
I also do think I have a coolant problem but unsure where it could be from. I have changed out my radiator, water pump, hoses and thermostat. I do not have a noticable leak on the ground but it is going somewhere. I do not have coolant inside of my oil because my dipstick doesnt show a milky residue. It could be leaking outside the intake manifold, so I may change them as well. Any other suggestions would be greatly appreciated.

Even if you are getting a little coolant inside, it washs the oil on the
lifter(s) and you will get the noisy lifters on start up. Also leaky intake gaskets that leak into the oil does not always show up as frothy/milky oil. Of course if you have a signifigant leak, thats where you usually see milky oil. I am not a big believer of engine flushes, with the exceptioon of an auto-rx type of cleaner, where cleaning is gradually. I will say again though, try a bottle of GM oil supplement. It helps lubricate and free sticky lifters, etc, etc. I have used that stuff in numerous cars and I get very good results with it.

metallica21156
12-16-2009, 08:23 PM
could try running synthetic. my 95 used to tick. switched over. no noise since.

oneav8or
12-19-2009, 09:35 PM
Thanks blazes, I also have a coollant problem and like bandit I have no visable leaks of coolant and no evidence of dex-cool in the oil. Oil still has a brand new look almost clear and good oil smell, so I thought I ruled out intake/head gasket problem. Replaced the thermostat as I diagnosed the problem as the thermostat was not opening intermitatly, and dumping hot coolant out the overflow.
Could it be valve guide seals that are letting oil run back down to the pan when it sits for a while, then upon start up, the valves are dry and takes a few seconds for the oil to get pumped back up and lube the valves? It's def valve or lifter tap, but unsure exactly why they are taping due to lack of oil. Every mechanic seems to have a different theory, and hoping someone has fixed this so it's not just guessing and throwing labor and parts at it till something works.

Thanks guys for the info...please keep it coming if you have it.



Even if you are getting a little coolant inside, it washs the oil on the
lifter(s) and you will get the noisy lifters on start up. Also leaky intake gaskets that leak into the oil does not always show up as frothy/milky oil. Of course if you have a signifigant leak, thats where you usually see milky oil. I am not a big believer of engine flushes, with the exceptioon of an auto-rx type of cleaner, where cleaning is gradually. I will say again though, try a bottle of GM oil supplement. It helps lubricate and free sticky lifters, etc, etc. I have used that stuff in numerous cars and I get very good results with it.

blazes9395
12-21-2009, 01:42 PM
Thanks blazes, I also have a coollant problem and like bandit I have no visable leaks of coolant and no evidence of dex-cool in the oil. Oil still has a brand new look almost clear and good oil smell, so I thought I ruled out intake/head gasket problem.

This is a typical intake gasket leak. Its not bad enough to see it in the oil(yet), but its getting into the engine and causing your lifter rattle at start up. The coolant leaks past the gasket(s), and runs down the lifter valley right on top of cylinders 1, 5 or 2, 6 lifters. Leaving it like this will damage those lifters. But for sure though, its intake gasket starting to leak.

I'll say it again, as I have used this stuff several times, and always have had a good outcome with it, if you can't get at the gaskets right away, run some GM oil supplement in your oil. It will help keep the lifters from rattling and in general help the engine, it has a good additive pack to supplement your oil's additive pack. I do not generally believe in adding anything to your oil, but this stuff does help.

bandit7862
12-22-2009, 06:19 PM
This is a typical intake gasket leak. Its not bad enough to see it in the oil(yet), but its getting into the engine and causing your lifter rattle at start up. The coolant leaks past the gasket(s), and runs down the lifter valley right on top of cylinders 1, 5 or 2, 6 lifters. Leaving it like this will damage those lifters. But for sure though, its intake gasket starting to leak.

I'll say it again, as I have used this stuff several times, and always have had a good outcome with it, if you can't get at the gaskets right away, run some GM oil supplement in your oil. It will help keep the lifters from rattling and in general help the engine, it has a good additive pack to supplement your oil's additive pack. I do not generally believe in adding anything to your oil, but this stuff does help.


Blaze, do you have any tips or advice for taking on the task of changing out the intake manifold gasket? Maybe some websites or publications or anything. Looking over the Haynes manual, this is no small job and obviously it has to be done exactly right with zero mistakes or I may ruin my engine. I am going to do it myself because a repair shop will want at least a grand to fix, so if anyone has any tips or tricks, please let me know. Thanks a bunch.

bandit7862
12-22-2009, 06:25 PM
I forgot to mention that I am also losing power on my 04 Blazer. It justn doesnt seem to want to get up and go anymore. Could that be because I am losing coolant thru my engine or intake manifold? If I hit the gas too hard, it will cause misfire codes to set, kinda like I am losing power thru cylinder compression??? I dont know, but I hope changing out the intake manifold gasket will tell me alot. I am also wondering if now would be a good time to change out the oil pan gasket since there was sludge in the bottom at one time. But the Haynes manual says to remove the 4 wheel drive parts to remove the oil pan gasket??? Anyone have any advice on the best way to do this? Any information would be great. Thanks.

blazes9395
12-22-2009, 07:01 PM
I do have a few tips to help you...
Here is a link to the tech section on here that gives you a good start on how to get the job done with the intake gaskets.
http://www.automotiveforums.com/vbulletin/showthread.php?t=879228

and another;

http://d-tips.com/General/Articles/article.aspx?id=/free/How%20to/GM%204.3L%20Intake%20Manifold%20repair/43intakearticle.art

These two are the best I have seen on the net, there could be others, but these two I like.


Before taking the intake off, try to clean as much dust, dirt, grease off the engine top as possible, you want to keep it as clean as possible, so none of that stuff gets inside the engine and damages your bearings. I myself just before I start any gasket job, I take the alternator off and any other removable parts and take a pressure washer to the engine. I cover any holes entering inside the engine though.

When buying new gaskets for it, if you plan on keeping the truck for a while, get the problem solver set made by Felpro. These gaskets do solve the intake leak problems associated with the OE gaskets.

Another thing I will mention here, when you are getting the gasket surface clean on the heads, I always hit it with a can of brake cleaner. The cleaner the better the gaskets will seal in the long run, you want no oil residue here.

Its a good idea to leave the oil in the pan(engine) as you are getting the engine ready for new gaskets. The reason for this is as any dirty does get inside, the light stuff will float in top of the oil. Just before your ready to install get a bottle of cheap/cheapest oil you can find and pour it all over the inside gallery/lifter valley. The idea here is to get all the dirt that has gotten inside the engine to go down into the pan. At this point take you oil pan drain plug off and drain the oil out of the engine. Any dirt that has gotten inside will at this point pretty much drain out with the old oil. You are ready to install your gaskets at this point.

Another fact worth mentioning is when you are ready to torque your intake bolts on, make sure you follow the proper torque sequence. This is very important and if not done correctly, you run a risk of ruining your engine. Follow the proper torque sequnce though, and you'll be fine.


In your case, when was the last time a tune up was done? Plugs and wires? When you change your plugs anytime, always use the delco platinum plugs. People have had trouble with other brands, misefires, rough running etc, so its just easier to avoid the hassle and put in the originals.

As for the oil pan, anly the 4x4 models can really be done with the engine not removed and hoisted up, but the front differential has to be removed, there really is no other way. The haynes manual and others say to just unbolt it and move it forward, but that is very hard and you run a risk of getting dirt inside the engine. If its leaking, i have seen many pans on these trucks that have lost thier oil pan bolts. Look carefully for that. Retourque them and you should be alright. Obviously a new pan gasket is the best way to go, but if you don't want to pull the front diff, that may be another option to take a look at.

Oh yeah, if you do replace the oil pan gasket, replace the remote oil cooler to block block gasket, and take a good look at your oil lines, if they are leaking, this is the easiest time to replace them.

Any more questions, just ask.

oneav8or
12-31-2009, 11:27 PM
Thanks again Blazes. Unfortunatly you are right (as usual), and my intake manifold is leaking. Borrowed a pressure tester and found the small leak from the intake manifold. Thanks for the info, as I will be also changing this myself. Will report back when I'm finished.

bandit7862
01-01-2010, 08:29 AM
Thanks again Blazes. Unfortunatly you are right (as usual), and my intake manifold is leaking. Borrowed a pressure tester and found the small leak from the intake manifold. Thanks for the info, as I will be also changing this myself. Will report back when I'm finished.

oneav8or,

Where did you get the pressure tester from and how exactly do you hook it up? If this is the best way to check for a leaking intake manifold gasket, I want to try it before doing this huge job. Also, before I am able to attack this job, I have been changing my oil about once a month just to keep it running and it has been keeping my lifters fairly quiet temporarily. My lifters start ticking again when cold about 3 weeks to a month after the last oil change. Lastly, It was getting expensive to keep pouring dexcool into the radiator and reservoir, so I heard I could use the green anti-freeze instead of the orange dexcool. I was losing about a quart of coolant every week or two with no visible signs on the ground or around the engine. That is why I was asking if I could be losing this coolant out the exhaust manifold because I cannot find a leak. Maybe it is leaking out the exhaust while driving. Is this possible? I now have heard that you should never mix the 2 colors of anti-freeze. I am not sure which is correct. Any suggestions would be great to know.

labs4ever
01-01-2010, 10:16 AM
My 2000 blazer had tappet noise from day one. About 3 years later I threw caution to the wind and I used the old trick we used in our tractors for loud engines. I replaced one quart of engine oil with 1 quart of Marvel Mystery Oil. Aftera few days the noise has stopped and now I use it every oil change. However, I change my oil every 2000-2500 but just because I work my blazer alot harder than it should be.

labs4ever
01-01-2010, 10:35 AM
You can buy the pressure tester at any automotive parts store. It sounds as though that you have probably lost a head gasket, probably around the number 3 cylinder. Usually the intake gasket will leak at the upper part of the intake ports of the number 1 and 2 cylinders. I have done a few of these in the last couple years. I took preventative measures when I bought my truck. I knew of the Dex-Cool issue so I immediately flushed my entire system and went with a coolant usually used in RV generators. Its a yellowish green made by Prestone. I have had it in my truck since 2003 and no issues.

dab1123
01-01-2010, 12:47 PM
To all with cold temp. tapping issues & all concerned with proper care of vehicles:
While I am not permitted to advertise on this site/blog, I would like to assist everyone with lubrication, filtration tips & vehicle longevity.
Contact me:
Web site: http://www.lubedealer.com/worldsfinestsynthetics (http://www.lubedealer.com/worldsfinestsynthetics)
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bandit7862
01-02-2010, 08:07 AM
My 2000 blazer had tappet noise from day one. About 3 years later I threw caution to the wind and I used the old trick we used in our tractors for loud engines. I replaced one quart of engine oil with 1 quart of Marvel Mystery Oil. Aftera few days the noise has stopped and now I use it every oil change. However, I change my oil every 2000-2500 but just because I work my blazer alot harder than it should be.

labs4ever,
does that marvel mystery oil really work or is it just another money making name? My 4.3 liter engine only taps loudly when it is cold, but a few days after the oil change, it is quiet as a bug. My Blazer works hard too and usually running it about 75 to 100 miles a day. If you think that mystery oil will work, hell, i'll try anything to get this embarassing lifter ticking to stop. Thanks for the tips.

labs4ever
01-02-2010, 11:19 AM
Well, I cannot guarantee anything being a consumer, all I can tell you is the results we have had using it. My father ran mystery in is 1984 suburban, the body is all but gone, engine has just under 400k on it. Our 96 Suburban has 270K on it, my 90 Sierra has 230K on it, the Blazer that I work like a mule has 214K on it. The only vehicle here that hasn't some kind of extreme duty is the 96 Suburban, it only tows a small sailboat, everything else is farm related. The Blazer is my personal workhorse, it tows hay wagons, gravity bins, plows snow and it urges a few cattle now and again with the front bumper/cattle guard to go in the right direction. Another person I know who swears by Marvel is a friend of mine who uses Marvel in the fuel and oil of his Cessna 310 twin engine airplane. Not only does it clean and lubricate the valves, injectors, it also has reduced the wear found on the internals during the required engine overhaul times. I hope I have given you reason to try it at least. Oh, and we use it in our 1926 Farmall tractor also.

oneav8or
01-04-2010, 10:23 PM
Sorry it took so long to get back to you bandit...been working for the last day changing the intake manifold gasket. Went pretty much as advertised, just took a while to get everything off so I could remove the manifold, and then a quick inspection showed...(drum roll please) the gaskets where in bad shape, broken in several places and obvious signs of collant leaking and one in particular, leaking into the top of the engine down into the cam (was the drivers side rear of the manifold). Took me around 7 hours maybe, with all the cleaning I did. That guide blazes posted was pretty much right on, except the newer blazers there is no way to move the electrical harnes bundle out of the way, and you need help to hold the bundle up so you can get the manifold back in. I did not remove the fan, but I did remove the alternator as it was easier to get to the heater hoses and something else (can't remember what).

As of today it's not leaking, and no tapping on start up....although with new oil, it didn't do it anyway......but there is a tick coming from the bottom of the engine....hope it is not the main bearing damaged and getting ready to go.

Bandit, the pressure tester came from Autozone, one of those rent/borrow tool loaner things. It's self explanitory really, goes on where your rad cap is and has a bicycle type pump you pump up to pressure and look for leaks. I had one on the drivers side that I could see just barely trickling out on the front when pressurized...but never saw it there when the engine was just running at idle. That leak never made it too the ground while sitting at idle, but I guess the pressure wasn't high enough until probably highway speeds and it just spewed all over the bottom of the engine and wisked away by the relative wind. Yours sounds the same as mine though, and most likely is the intake manifold gasket leaking. DONT MIX THE TWO ANTI-FREEZES as you will end up with a brown sludge in your system that will gum up everything. Really it wasn't bad, and the hardest part I think was loosening the power steering bracket as the nuts (two on the lower part in the back) are kinda hard to get to I think. Have one other person help you, I had two volunteers actually that thought it would be good to see how it's done. If you are in the St. Louis area I would be glad to help out. I'm not an expert by any means, but I guess the water from the coolant is getting evaporated by the heat of the engine? The oil I drained did not seem to have any water in it, although it's heavier and would have sank to the bottom, but it was black, def not what I expected after only a few hundred miles, and it was thinner than it should have been for the miles since last oil change. I spent around 86.00 $ for the gasket, 2 gallons of prestone dex-cool (not premixed) and 2 gallons of distilled water, 5 quarts of oil and a filter. Had 3 quarts of oil on had already to pour though the upper part of the engine to "wash" all the crap down to the oil pan. Had to flush the heater core as I guess all the junk I didn't get, clogged up the heater core and my heat wasn't working. Sorry for the long post.

oneav8or,

Where did you get the pressure tester from and how exactly do you hook it up? If this is the best way to check for a leaking intake manifold gasket, I want to try it before doing this huge job. Also, before I am able to attack this job, I have been changing my oil about once a month just to keep it running and it has been keeping my lifters fairly quiet temporarily. My lifters start ticking again when cold about 3 weeks to a month after the last oil change. Lastly, It was getting expensive to keep pouring dexcool into the radiator and reservoir, so I heard I could use the green anti-freeze instead of the orange dexcool. I was losing about a quart of coolant every week or two with no visible signs on the ground or around the engine. That is why I was asking if I could be losing this coolant out the exhaust manifold because I cannot find a leak. Maybe it is leaking out the exhaust while driving. Is this possible? I now have heard that you should never mix the 2 colors of anti-freeze. I am not sure which is correct. Any suggestions would be great to know.

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