Broken Intake Manifold Bolt

dfire

Active Member
So.... I'm back. In the last 2 months I have replaced the water pump , Fan clutch , Power steering lines , idler pulley , and ball joints. I did also chaged the DIF & Transfer case fluid but that's just routine maintenance . Anyway..... Ive had alot of help from you guys and I clearly couldn't have done it without you so Thanks! So I have a cracked intake bolt. its the second row from the front on the bottom (I will post a Picture). Im getting rather exhausted from the back to back issues I have had. What are my options on fixing this and how much damage is it getting from being used? I know the idea of it creating a vacuum leak and what not. Just needs some help again. Thanks
 

Attachments

Mooseman

Moderator
Pics aren't clear. Is it the bolt or manifold that's cracked? Either should be easy enough to replace. A used manifold should be easy and cheap to get. Haven't heard of any failures of these manifolds before.

I know it sounds frustrating but these trucks are at least 10 years old now with mileage to match. Things get old and break.
 
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dfire

dfire

Active Member
Yeah it’s definitely getting up there in it’s life span. It’s just been a lot of things for a short period. I also have o2 sensor to install lol. When I clicked on the pictures on my PC and phone I could view it just fine. The bolt itself is hanging. I tried to tighten it down but it won’t catch. It’s the bottom bolt in the picture if you look you can see the gap and angle. I’m removing the unnecessary picture. I don’t mind working on it I just want to start working on my other project. I have a whole engine I plan on rebuilding. I guess my big question here is can I get away with not fixing it right now or is it going to let moisture in and start doing some heavy damedge. Strangely enough it seems to be running a bit better but I did check and make sure all the other bolts where to spec which is probably why.
 
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budwich

Well-Known Member
you can check things like fuel trims to see if there is "extreme" values indicating significant intake "ingression". Further, you can do a "spray test" to see how the engine responses. these will give an indication of how bad the leak might be in its current state. IF it is significant, you run the risk of causing cat problems with the potential of excessive fuel injection.
 
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dfire

dfire

Active Member
Thanks @budwich. I’m replacing the o2 sensors today. I was only going to do the upstream but the downstream has been stuck a 99% for a little while now so I’m thinking there might be an issue there. I’ll let yuh know what I get. Thanks

Pictures are from before tightening manifold to spec. I can’t tell you if I broke that bolt or it’s been like that. It seemed loose already.
 

Attachments

budwich

Well-Known Member
My read on those values would seem that there is little to no "extra leaks" as the LTFT seems pretty neutral.... not overly deflected in pos/neg direction. Of course, that could change depending on run time / heating effects. A "spray test" and engine response may tell you a bit more but it does not look like you have an issue currently / at the time of the measurements.

As for moisture getting in... as long as you aren't injecting a "water stream" (ie. off roading, water jumping), moisture / vapor will actually clean your cylinders... kind of like a "stream cleaning".
 
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dfire

dfire

Active Member
Well once I get the o2 sensors changed I’ll post new results. The bank 1 sensor 2 STFT is not suppose to be stuck that 99% right? From what I understand it’s just post CAT readings for heat. My guess there is to determine if it’s clogged or not. That’s just my educated guess. For awhile now I have had idle issues and a pretty big loss of power. Every time I go up a hill this things struggles. Sense cleaning the throttle body. Replacing air filter , fuel filter, spark plugs(AC Delco) and making sure CPS bolt was torqued properly it idles normal for the most part.I still have an issue with it getting up to speed and climbing hills.The hills are really bad. I left cruise on and started going up on at about 55 MPH and it jumped up to 4K RPMS to maintain. Fuel pump was replaced 20k miles ago. Still need to check the pressure though
 

Mooseman

Moderator
OK. Now I see the problem. Try pulling the bolt out. I think they're just held in by an o-ring. If it's broken.in the head, you have to pull the whole intake and remove the broken end. If the bolt itself just has damaged threads, you could just get another one.

That bolt is twinned with that tip bolt. Maybe it'll be fine without it. Do you have an intake leak? Check the others.
 

budwich

Well-Known Member
sorry, now that I relook at what you posted in the data attachments, I am not sure that understand some of the "outputs".

you are looking at the 99.2% for the o2 sensor reading but I dont understand that... normal it is a voltage reading usually between .1 and .9 and then depending on run time, "flat lined" somewhere is maybe the .6-.8 range.

Having said that, your data system may be correct inn some form. Most people (me included) "think" that the post o2 sensor doesn't have any impact on trims / fueling but if your system data is correct, it would appear that it does. Doesn't surprise me as I kind of have been wondering why various "funny things" happen in around trims and monitoring o2s and the correlations dont seem to be close with just the forward sensor.

further... I was looking at the wrong trim data... for picture... sensor 3.... not sure what that is.
the last picture indicates a short term trim of 7% with a range. That range seems rather high and would expect it to be lower more neutral assuming you weren't "goosing" the engine during the capture.
 
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dfire

dfire

Active Member
@Mooseman Ill check it out this coming up weekend and see what I can find out.. The threads getting messed up is possible considering it just felt loose in there. Honestly that thought never crossed my mind so fingers crossed. I'm truly dreading removing the intake lol. @budwich Well I did not get around to replacing my sensors today but I did go ahead and see how bad the leak was and I can hear a little squeal so I clearly messed up that bolt and you can ignore sensor 3. I accidentally put some useless metrics in that table that I have yet to remove. That being said the RPM is shown in the pictures so you have a reference it was going about 2k. I'm sure @Chickenhawk is right about the CAT as well. My downstream voltage is literally just mimicking the upstream with about 1/2 second delay and with the symptoms being the same as what i've had going on
 

budwich

Well-Known Member
thanks for the extra clarification. yes, a post cat sensor that is not "flatlining" at some "good value" is likely indicating an issue with the cat... although, the cat does have to come up to temp before the "cycling" of the post cat sensor stops.

On the bolt, you may be hearing a leak thru the bolt hole itself as opposed to a "mating surface leak" of the intake itself. If you don't want to work on the intake or the bolt removal itself, you might try a temporary bandaid using a "dab" of sealant to see if that helps.... of course, you want it to be non-silcon based to not cause o2 issues there after.
 
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dfire

dfire

Active Member
A dab of sealent over the bolt hole or with the bolt in it? Also can you recommend a sealent.
 

budwich

Well-Known Member
I can't directly as I found someone had put some sealant on one of the screws holding my MAF into the air intake tube.... hence the idea. This would certainly be a temporary "fix" and assumes that the overall integrity of the main surface areas of the intake are "good". I would look at some like gorilla glue clear which I have used for other things... It dries well and I don't believe it has any silicon in its structure. | would just "blob" it over the existing bolt to seal the whole thing in place.
 

Mooseman

Moderator
A downstream O2 sensor showing basically the same as the upstream means your cat is dead and not cleaning the exhaust and should throw a code for it. That's all that sensor does, report if the cat is working.

Definitely a good idea to check for vacuum leaks using carb cleaner.
 
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dfire

dfire

Active Member
ok so sorry for the delayed postings on everything. I feel bad about not getting back sooner sense you guys are so good about helping and responding quickly and I left the story without an ending lol. Anyways, I replaced the upstream o2 and that made the truck run A LOT better even going up hills. freaking PIA to get out. the downstream sits evenly around .6 or .7 when warm so i misdiagnosed that issue. I also replaced my spark plugs again with the proper 41-103. I was using the AC-Delco rapid fire and im willing to bet that was contributing to the all around effects as well. Tonight I plan on finishing up sealing that bolt until I decide what to do next. I seriously cant thank you guys enough for so much help. Ill try to donate a little to the cause :smile:
 

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