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Sorry this is a long read but I’m having issues. I’m not a mechanic but, me and a couple friends are replacing the head gasket on my Tahoe. We have got it all put together but, now it doesn’t sound right. First, it will not start. All it’s doing is backfiring. The weird thing is that it only seems to do It on the drivers side of the engine. It’s almost like the right side has nothing at all. When you try to crank it sounds like its rotating but there isn’t any combustion at all. (I’m not sure I’m wording this correctly). When doing the normal checks. There is new fuel. I’m at least getting it to the injection system and when we remove the plugs they are wet and smell of gas. We have gotten the motor to TDC. And then we dropped the distributor with out the cap on to make sure the distributor was lined up correctly. Then tightened it and put the cap on. We’ve double checked the wires to make sure they are correct. All of the wires are connected to their correct parts. The exhaust manifold is connected just not to the pipes. So we can make sure it runs and that we don’t have to disconnect later.
The reason we changed the head gasket was because a couple years ago the truck overheated. Since then the service engine soon light was on and everywhere I went to scan said the same thing. Cylinder 4 misfire. Later I learned that those engines are notorious for cracking the head when over heated. Once we got it a part sure enough cyl 4 cracked on the head. The block was fine. I was still able to drive it sparingly after the overheat so I’m pretty sure it was just the head. It never overheated after that or even had problems. Once I saw the head I ordered new stock heads from autozone, gaskets, pushrods, (because I dropped a couple when we removed them), plugs, wires, water pump, belts, hoses etc. pretty much everything I could that would be easy during all of this.
I have not checked the compression yet because none of us had a compression gauge with us. I plan to get one this weekend and check that too. I am hoping someone has run into this and at least give me a few ideas to look for. Thank you for any help you might be able to provide.
Oh and btw, if anyone else has to go through this. It’s almost just as cheap to buy a whole new motor from autozone or advance. I have probably about $1300 into it and the last time I checked a long block was another thousand and then you just had to bolt it on.
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Sounds like you may have the distributor installed 180 degrees off. pull # 1 plug and turn motor over by hand. you can put a small piece of paper over the plug hole and it will blow off when you hit the compression stroke. make sure to check the t/marks on the balancer to see that they align with tdc mark ( on compression stroke ) now pull the dist cap and see where the rotor is pointing. if not pointing at # 1 then pull dist up until it clears the cam gear , turn rotor twords # 1 and reinstall. check this first and post back your findings .
We thought the same thing, we tried 180 4 times and it didn’t matter which way we had it, we got the same result. The last time we had an Chevy enthusiast come and look and he said he “thinks” the last position it was in was correct. He was at a complete loss but, he did say that he is not used to work on stock engines and trouble shooting them. He is more of a circle track guy. Would a distrubutor that is 180 out cause only one side of the engine to backfire. The driver side is the side that seems to back fire. Never on the passenger side. And by that I mean, that is the only side we see fire out of the exhaust manifold. I am thinking it might be a compression issue internally.
have you pulled the valve covers and verified all push rods are seated properly ? a compression test would be the next step.
I did one of these… exactly what you are doing…
Q: How are you setting your timing?
Setting the timing on this engine is not as easy as you’d think. You have to study the prodecure very well. You have to ensure that you get then engine in ‘base timing.’ GM on this particular engine used a procedure that refers to a ‘cam retard offset window’ that you have to account for when you set the timing. So.. you’ll probably need a scan tool.
When I was doing this, I had a hell of a time setting the timing right because I didn’t know the procedure for this engine, nor did I know anything about ‘base timing mode.’ I shot the timing gun on that engine all day long and got no where. It was essentially a battle of me vs. engine computer for control of the timing and we were both in a deadlock.
I later learned how to do it right when I read the procedure out of a Haynes manual.
I’m not sure how to check that pushrods are seated properly. We have pulled the valve covers. I was in the truck so I couldn’t see what was going on. What would I be looking for.
The vacumn gauge however, I’m planning on getting this weekend. While I realize tools are a personal choice, how does this gauge sound?
http://www.sears.com/actron-cp7827-compression-tester-kit/p-00902171000P?prdNo=16&blockNo=41&blockType=P41First with the key we bump started until we got close to TDC then we manually went the rest of the way. Then we pulled the cap and checked the status of the rotor. Tightened everything up an tried to start it. No luck. We then loosened everything up and turned 180 and restarted the process again. Still no luck. In order to use the timing light doesn’t the truck have to be running. When you had these problems, did the engine sound like it had compression. I will try to get something recorded so I can play it for y’all. Mine sounds like everything is turning within the motor but no compression. At first I thought the starter had went out or wasn’t making contact with the flywheel. It sounded like metal turning that’s it.
i hate to second guess you, but i only ask this because it was an issue during my head gasket repair:
Q: how confident are you about your spark plug wiring vs. firing order
[quote=”Wrench Turner” post=49901]i hate to second guess you, but i only ask this because it was an issue during my head gasket repair:
Q: how confident are you about your spark plug wiring vs. firing order[/quote]
No offense here, I’m a rookie at this. Up until this point the most I’ve ever done related to the external engine only. Alternators, batteries and brakes, heck I’ve done more with lawn mowers than I have with cars. To answer your question, I’m not sure. The reason I say this is because I wasn’t the one that did them. I know the first time we looked at the book because I read them off. After that my friend said he knew it. I do trust him though. He was a manager at meineke until he realized he could make more installing house windows. I work at a hospital 12 hours a day, 4 days a week. I’m not off again until Sunday but, I will double check them then.
With the valve covers off make sure the pushrods are seated both on top of the lifters and under the rocker arms. did you do an initial adjustment on the rocker arms before trying the first start up ? since you mentioned no noticable firing on one side a compression check there might reveal answers. check it both dry and wet. the actron guage is fine. I have that same one. I am assuming the timing chain/gear assembly was not touched during the repairs. also , I would verify that all plugs are infact getting spark.
[quote=”619DioFan” post=49905]With the valve covers off make sure the pushrods are seated both on top of the lifters and under the rocker arms. did you do an initial adjustment on the rocker arms before trying the first start up ? since you mentioned no noticable firing on one side a compression check there might reveal answers. check it both dry and wet. the actron guage is fine. I have that same one. I am assuming the timing chain/gear assembly was not touched during the repairs. also , I would verify that all plugs are infact getting spark.[/quote]
Ok I will check the pushrods. We didn’t do any adjustments on the rocker arms. I think the only thing we did was just tighten the nuts. Do you know of any videos that show how to do this. Correct on the timing chain, it was never touched. We did check most of the wires for spark. I cannot confirm he did all because I was the one turning the key. What does wet/dry mean?
perhaps I wasn’t specific enough. Please allow me the opportunity to clearify:
Q: When you put the engine back together, did all the spark plug wires go back to the spark plugs in which they came from? Similarly, did the spark plug wires go back on the distributor cap in the same order in which they were removed?
I only ask because when I did head gaskets on this engine, I also had to put in new spark plug wires which took a bit of time because they are all different lengths… so I had to devise a method to determine which plug wires would be suited for which cylinder in accordance with the firing order.
Just google rocker arm adjust for the truck , sure you will find something. take me too long to type it out ( sorry – very poor typer here ) use a spark plug tester to verify spark at all plugs. wet – dry compression test means- dry: test the compression as normal.
wet : add a little oil to the cyl and then retest the compressionif the compression changes dramaticly ( increases ) during the wet test then you probably have a ring/cyl wall prob.
[quote=”Wrench Turner” post=49910]perhaps I wasn’t specific enough. Please allow me the opportunity to clearify:
Q: When you put the engine back together, did all the spark plug wires go back to the spark plugs in which they came from? Similarly, did the spark plug wires go back on the distributor cap in the same order in which they were removed?
I only ask because when I did head gaskets on this engine, I also had to put in new spark plug wires which took a bit of time because they are all different lengths… so I had to devise a method to determine which plug wires would be suited for which cylinder in accordance with the firing order.[/quote]
I believe so yes, however, they off been of so many times since then that I will double check.
[quote=”619DioFan” post=49912]Just google rocker arm adjust for the truck , sure you will find something. take me too long to type it out ( sorry – very poor typer here ) use a spark plug tester to verify spark at all plugs. wet – dry compression test means- dry: test the compression as normal.
wet : add a little oil to the cyl and then retest the compressionif the compression changes dramaticly ( increases ) during the wet test then you probably have a ring/cyl wall prob.[/quote]
Ok will do!
Thank you for all of your help. Here is my to do list for this weekend. I will post back with results and hopefully video as well.
Read up on setting the timing
Check the plugs and wires and firing order
Recheck timing/set the timing
Check compression dry/wet
Check rocker arm settings.
Get video of before/after everythingOnce again fellas, I really appreciate everything you have done and recommended. I’m hoping something here will work. I have had numerous people look and no one has been able to pin point the problem.
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