Does anyone have an idea as to what my truck's problem is based on this info? To give you some background on my vehicle it is a 1998 Chevrolet Tahoe 2 DR WG Z71 4X4. I bought it with 90K and since then I have maliciously maintained it. I have owned the truck for almost 3 years now and it has about 153K. Since I have owned the truck I have had GM put a new t-case in it, rebuild the rear end, replace both the front axel and rear axel seals all around, put a new steering box in, install a new idler and pitman arm, replace the CV Axels, install a new starter, and just last week I had GM put a remanufactured 4l60e transmission in it. Did I mention that all of the above parts are GM Delco/Goodwrench parts and that those items are just mentioning the major stuff? I have done all the oil changes at or before 3k, I did a tune up on the truck with Delco parts about 20k ago, and the truck has new Delco pads in rotors in the front and new pads in the drums in the rear. I guess you could say I love my 2dr Z71.
Now I have a new problem. Yesterday morning I went to crank my truck and all I got was a struggling noise from my starter fighting against what seemed to be a stiff motor that was accompanied by a nasty metallic noise. After doing a couple turns of the key for four and five seconds at a time I got the engine to fire up but it was struggling to run in that it was idling rough at about 250rpm- 400rpm. After giving it some gas it started idling at the normal idle speed of 500 or so rpm. However, when idling after the initial startup, the motor has a loud ticking noise that eventually would completely go away after driving the truck for a few minutes. After that the truck ran normal. I have never had this type of tick come from my motor. I did have an exhaust leak that I fixed two weeks ago by replacing the donut gaskets on the down pipes coming off the heads. After replacing the gaskets my motor ran as quiet as a new vehicle. This new noise is not the same type of tick as the old one I had before with the exhaust leak. The new tick happens when the truck is idling versus when the tick related to the exhaust leak would cause the motor to make a ticking noise when it was loaded up upon acceleration. I am now wondering if the valves were forced to re-seat themselves due to the stronger back pressure or if I a sticky valve due to carbon build up have caused a valve to seat off spec. I don’t think I have a burnt valve because this morning after running the truck 20 miles up the highway she still had the same serious pick-up without any hesitation as a new V8 vehicle. Going up a slight hill this morning, my old girl could still jump to 60 in about 7 seconds flat. Not to shabby for a stock 1998 Tahoe. Beyond looking at the valves, could a bad oil pump be causing this issue with the ticking and how would I diagnose that problem. Is it possible that upon initial startup that my motor is starved for oil and that the lack of oil pressure is the reason for the rough metallic noise occurring when the starter turns the motor over? Couldn’t that oil issue also explain the initial ticking that occurs when I start the truck and run it in the first couple of minutes? The engine has not thrown any check engine lights and the oil pressure gauge seem to be indicating normal operating pressures upon startup (Somewhere between the middle and the ¾ pressure mark on the gauge.
Please give me your thoughts on this issue. Also, could someone give me an idea as to what my next step should be in order to diagnose and fix my trucks problem? I don’t want to take it back to the dealer as I have already spent my piggy bank on the tranny and other repairs. I am thinking of grabbing a mechanic friend to help me do the repair myself or having a trusted local shop (they don’t usually stock or sell AC Delco ) do the repair so I have a warranty to fall back on. If anything I would like to have idea of what I am faced with before I go into a shop and then also have some good questions to ask the shop to insure that they do a correct and complete job and fix this problem the first time.

I use rislone for lifter tick- works every time! Buy it most anywhere- like Autozone.

After lunch today I took the truck down to the local auto parts store. When I initially fired the truck up I had the same tick and my oil pressure was reading around 80psi or 4/4 on the indicator in my gauge cluster. I purchased a bottle of Magical Mystery Oil (solvent) which is designed to clean and un-stick valves and other internal components. I poured the product into the crank and it seemed to immediately improve the problem. Upon start-up I did not have any ticking noises. My oil pressure on the way back to the office which is about 4 miles away from the auto parts store was reading normal as I went through the gears down the road at about 50mph. I do want to note that I did see some small speaks of oily sticky gunk on my dip stick when I first checked the oil this afternoon. I will give an update as to how the truck runs tomorrow morning when I first crank it as this is where the initial problem has occurred for the last two days. I should have a good 25 highway miles under the motors belt with this product in the crank case by tonight. I will keep y'all updated.

I also plan to check that the valves are set correctly by doing the old dollar bill trick where you place a dollar bill up to the muffler and see if it consistently blows the bill out or if the engine tries to suck the bill into the pipe. I will update tomorrow.

Okay so I did the dollar bill test and what I found was that every seventh or eighth "loop" of the engine the muffler would try to suck my dollar bill in instead of the exhaust blowing it out. Any thoughts on this note as to whether it explains the oil pressure and rough start when cold? I do want to indicate that my motor seems to be healthy in terms of the coolant levels and the oil levels staying constant. About 6 months ago I did run into a misfire code on one of my cylinders while towing my 17 foot ski boat up a hill while at hwy speeds and unfortunately I did not write the code down. Oh well, hindsight is always twenty-twenty. Since then, I have not had any check engine lights come on. I also want to note that the tick came back when I fired the truck up after letting it sit for a couple hours. Maybe the Magical Mystery oil hasn't worked its "magic" yet? I will probably change the oil if things don't improve by tommorow. Any help is most appreciated

Okay so I did the dollar bill test and what I found was that every seventh or eighth "loop" of the engine the muffler would try to suck my dollar bill in instead of the exhaust blowing it out. Any thoughts on this note as to whether it explains the oil pressure and rough start when cold? I do want to indicate that my motor seems to be healthy in terms of the coolant levels and the oil levels staying constant. About 6 months ago I did run into a misfire code on one of my cylinders while towing my 17 foot ski boat up a hill while at hwy speeds and unfortunately I did not write the code down. Oh well, hindsight is always twenty-twenty. Since then, I have not had any check engine lights come on. I also want to note that the tick came back when I fired the truck up after letting it sit for a couple hours. Maybe the Magical Mystery oil hasn't worked its "magic" yet? I will probably change the oil if things don't improve by tommorow. Any help is most appreciated

on the marvel mystey oil....only use 5oz. max and after a few hundred miles change oil....only change the oil when hot...drain for 1/2-1hour...


if black goop is on you dip stick you will need to repeat oil changes as this goop must be removed.....use high quality oil filters wix, or pure one by purolator....do not use FRAM.....


it is possible the you cat is getting restricted as the exhaust gaskets got blown out......150,ooomi is normal for this failure....


change PCV

I usually have the GM dealer change my oil as they always have 5.95 oil change coupons floating into my mailbox and I get a decent filter and oil out of it. In response to J Cat's comment, I used the entire Magical Myster Oil bottle which was 16oz??!!? Do I have a potential problem brewing as a result of that?

I usually have the GM dealer change my oil as they always have 5.95 oil change coupons floating into my mailbox and I get a decent filter and oil out of it. In response to J Cat's comment, I used the entire Magical Myster Oil bottle which was 16oz??!!? Do I have a potential problem brewing as a result of that?


yes that is tooo much.....5oz is all you need...replace your oil as I said and put 5oz of the marvel in...then keep checking the dip stick for carbon/sludge ,then replace oil when hot.....as soon as goop appears..again..


On the GM dealer oil changes I have several free coupons for oil changes I would gladly give them to you but then that would make me guilty of damaging your vehicle...this may be why you have a goopy oil condition and engine noises....make sure the forgotten PCV is replaced....

So the root of my problem is a leak in my Air Intake Manifold Gasket which is very typical for this model vehicle. It seems that the coolant is mixing with my oil and causing my lifters to float. I luckly just noticed the noise and parked the truck so I am hoping that the lifters will blow back out. I probably have put about 400 miles on the vehicle since the leak first occured. I am guessing that the noise goes away once the car warms up as most of the Coolant that gets down into the crank oil evaporates out of the PCV valve which I do plan on replacing. Correct me on that statement everybody if I am wrong. Hopefully this works out. I plan on tearing into this repair myself this weekend. I might have a few questions while working through the job which I will post in the thread DIY Intake Manifold gaskets. Thanks for the help everybody.

So the root of my problem is a leak in my Air Intake Manifold Gasket which is very typical for this model vehicle. It seems that the coolant is mixing with my oil and causing my lifters to float. I luckly just noticed the noise and parked the truck so I am hoping that the lifters will blow back out. I probably have put about 400 miles on the vehicle since the leak first occured. I am guessing that the noise goes away once the car warms up as most of the Coolant that gets down into the crank oil evaporates out of the PCV valve which I do plan on replacing. Correct me on that statement everybody if I am wrong. Hopefully this works out. I plan on tearing into this repair myself this weekend. I might have a few questions while working through the job which I will post in the thread DIY Intake Manifold gaskets. Thanks for the help everybody.

If the coolant level drops the oil fill cap has mositure and the dip stick has goop sludge on it it is most likely your problem....my question is did you keep/maintain the coolant system, and did you use the proper dexcool antifreeze with the GM spec number on container ???

The coolant was changed when I did the water pump at 90k. I did indeed use the Dex-Cool fluid when I re-filled my radiator and overflow tank. I have read that Dex-Cool isn't as great as it is cut out to be and it is best to switch from Dex-Cool to a differen high grade anti-freeze? Any thoughts on this?

As long as you properly flush the system running a different coolant is no problem. I am currently studying for a Automotive degree and have not once heard a good thing about dex-cool. In the shop we have always flushed the car with regular coolant and tagged it under the hood.

I personally run a coolant called made by Pro-Blend desgined to keep temps from rising fast in my Trans Am . And I have to say that once on the highway and getting stuck in traffic it takes a while longer for the motor to heat up. I got it through my work alot cheaper than other auto parts stores. Though in my Daily driver which is a Honda I run the Regular " Green " coolant The Pro Blend coolants are not for winter use how ever I dont drive the nice car then anyways


As well on the Oil Issue. I always used to usa either a Fram or Delco Filter. I made a switch to Wix filters and gained quite a bit of lost pressure

The coolant was changed when I did the water pump at 90k. I did indeed use the Dex-Cool fluid when I re-filled my radiator and overflow tank. I have read that Dex-Cool isn't as great as it is cut out to be and it is best to switch from Dex-Cool to a differen high grade anti-freeze? Any thoughts on this?

the use of non dexcool antifreeze will cause many problems as this engine was designed for dex-cool coolant...as you know you cannot flush out this engine and then be able to add the proper amount of coolant... you can only drain out about 1.75 gallons.....this system holds 4 gallons....unless you know a trick to drain the engine [I tried] you must be carefull to get the minimum of 50%....also as you probably know you need a special tool to measure DEX-COOL concentration ...If the container has the GM spec on it, it is DEX-cool,,,,, if it says its [compatible] it is NOT DEX-COOL.....


there are vehicle owners that have said they had problems but if they get the vehicle serviced by some idiot lube jocky you think there gonna use the higher priced dex-cool to top off??????? then they blame DEX-COOL...


I have used dex-cool now since 1996 and I have no problems stays clear and no cooling issues...put some silicone based antifreeze in this engine and you'll be sorry.....

As long as you properly flush the system running a different coolant is no problem. I am currently studying for a Automotive degree and have not once heard a good thing about dex-cool. In the shop we have always flushed the car with regular coolant and tagged it under the hood.

I personally run a coolant called made by Pro-Blend desgined to keep temps from rising fast in my Trans Am . And I have to say that once on the highway and getting stuck in traffic it takes a while longer for the motor to heat up. I got it through my work alot cheaper than other auto parts stores. Though in my Daily driver which is a Honda I run the Regular " Green " coolant The Pro Blend coolants are not for winter use how ever I dont drive the nice car then anyways


As well on the Oil Issue. I always used to usa either a Fram or Delco Filter. I made a switch to Wix filters and gained quite a bit of lost pressure


since your gonna be an expert soon how do you drain a 2000 5.3 vortec GM engine....the drain plugs are locked in the block so how do we get them to un screw so this engine can be completely drained of coolant....

So I managed to get my lower air intake manifold gasket replaced hoping that I could put away my tools for a week or two. That was not the case. Replacing my lower intake manifold gasket has not solved my issue with the oil pressure being way high for at least the first 5 minutes of running the truck in the morning. After running the vehicle for a while, the truck eventually idles at what seems to be normal pressure but then rises sharply as soon as I start gradually accelerating from a stop light. Any ideas on what is causing this problem with my tuck. The truck has not thrown any codes after the repair and so far I have put about 50 miles on the truck since completing the repair last night. What should my next steps be so that I can effectively diagnose the problem?

The next step would be to attach a mechanical gauge to the engine to verify that the oil pressure is indeed high. The pressure increase coming on the heels of the manifold gasket replacement may point to a problem with the sending unit or its wires, since it is in the area of the distributor. Search this forum for instructions on attaching a gauge to the engine, I think I remember seeing some.

Are there two Oil pressure sensors on my truck or just one? I believe one of them is over by my oil filter on the block correct?

Shodid...I flushed all my dex-cool out and I been currently useing "Green" for the past 3 years with no problem!! I gently drain my radiator filled it back up with water and took off a heater hose...crank up my 96 tahoe left the hose in the radiator and watch the rusty dex cool come out my heater hose til the fluid turn from rust to clear and once it was clear I cut off my truck, took my bottom radiator hose off to make sure all the water comes out from both the block and radiator...put the hose back on and filled my radiator baack up with green!!