---Been a long time since I've been here but I'm back and I got a short story if you care to read If not scroll past the "----Break----" that follows this poorly written and overly long paragraph. I did use the search function and I did find useful "book" info but still throwing this out here to see what you all think based on personal experience... ---

Story:
I used to own a 99 2 door, 2wd Blazer that I bought in 07 at 50k miles and owned until 2013. I loved it! and I crawled these forums for hours on end finding all kinds of useful information to keep it running top notch even when it hit the 280k miles mark!!! That was until one night in 2013... A drunk Driver totaled it while parked So I went out and bought a Ford since my family was growing to 5 and I needed to tow a trailer rated more than the Blazer's capacity so it seemed like a good choice, right??? IDK... Fast forward to 2 weeks ago, the Ford decided to just give up and hand-grenade it's self Not going to go into detail but even though I cared for it, a design flaw for my year involving the cam basically left me without a drive-able vehicle in an instant and without warning). I now found myself looking for a decent vehicle for cheap that I can use while I saved up to replace or repair the giant SUV paper weight sitting in my driveway. I stumbled across an amazingly good looking, 1 owner 2001 Blazer 4x4 sitting at 150K miles and decided to pull the trigger. The Price was right ($1,500) The body and the interior looked almost new. One of the best-cared-for all original interior/exterior Blazers I have seen in a long time! Even the seat handle was original and intact!!! . I figured all that cosmetic love and care trickled down to vehicle maintenance as well and after an flawless test drive (slight rough idle but my 99 was also rough after 100k until I replaced and cleaned the usual suspects so I wasn't concerned) I was sold. Well I guessed wrong, shame on me I guess as I feel I should've caught some of these issues when I 1st looked at it but maybe my love for my 99 blinded me? 1st sign of trouble:... On the drive home after purchase, the dang thing overheated to 260 in almost an instant just a mile from my house. I opened the hood and found a heater core hose blew and all the coolant blew out. No big deal right?... well... (Maybe get more popcorn if u r still reading ) I let it cool down, called the Mr's to bring me some tools and made a bypass out of the remaining good hose. It was when I removed the hose I found signs of what appeared to be Stop leak??? maybe some rust too??? But I am familiar with stop leak from the 1 and only time I used it when I was younger on a 91 Cutlass and it did a mess on my cooling system and this sure looked like the same thing. I got it home and did a good cooling system inspection. I NOW!!!! just noticed the aftermarket radiator and continued to find signs of build up throughout the system. I tried to run fluid through the heater core... Plugged solid #great. I started removing cooling system components and found the whole thing to be NASTY. I replaced all hoses, T-stat, T-stat neck, Water Pump and flushed the RAD as it still looked "okay" also flushed the block using a closed loop "home made thingy" I made for my boat. Cooling System is now top notch, runs just below the 210 mark just like my 99 did BUT!!! now it had a more noticeable rough Idle and threw a cyl6 miss-fire fault... great. It's at this moment I take a good look at the ignition system: Original Cap, Original Rotor, Original wires & AutoLite Copper Plugs This is where I start to feel really dumb lol. I replaced everything with A/C Delco except for the wires (waiting on some too good to be true cheap A/C Delco wires to arrive in the post) but the current ones ohm within spec. Now of course I did a compression check during the plug replacement and fell within my general 10% rule and WELL within GM's 70% rule that I don't trust lol, and the vehicle no longer has the SEL or miss while driving but it still idles a bit rough. Now finally my question

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TL;DR Long story short I now own a 2001 Blazer that currently runs rough at idle and ran rough at idle before it overheated to 260 almost instantly due to a blown hose and was shut down right away. After solving the overheat I had a code for cyl 6 miss-fire and a rough idle worse than before. I addressed the "worse rough idle" with a full tune up (minus wires as they are in the mail but old ones ohm within spec) It runs better after full tune up, has great acceleration and smooth driving with no SEL after several long drives and tbh the rough idle is slightly better than before the overheat but it still has a rough idle. Now I have not cleaned anything yet (I.E... TB, IAC, MAF, ETC...) But I'm a bit concerned about my compression test results and would like to know if I'm being overly cautious due to the overheat. My general rule I've been taught growing up and from what I've read seems common that cyl psi is to be within 10% of the highest cyl psi and this is what I like to go by on my 4.3L even though GM says 70% is okay... idk. My results are 1)-170 3)-175 5)-174 2-)175 4)-180 6)-162... As you can see my concern is between 4&6, 162psi is right at the 10% mark for 180psi... but why is 4 so much higher and why is 6 so much lower? No signs of oil in coolant or coolant in oil, plugs looked older than dirt but otherwise no concern. I will be doing a block test once the only loaner my local auto parts store has is returned and I will be cleaning everything that should be checked and cleaned. I just wanna get some feedback on those 4&6 readings... should I be concerned or am I just up too late worrying?

If you read the whole post (sorry) lol but thanks in advance for any feedback
---James

 

Not a bad book to read - lol
I wouldn't worry about what little difference in comp you have { I've seen and run a whole lot worse } heck it could be as simple as some carbon build up ....
I would finish the tune / clean up and while I was at it I would do the fuel pressure tests as per sticky at the top of the second gen section ....

 

Thanks for the feedback odat, I feel a bit better lol.
Ahhhh the fuel psi test I forgot about that, will do it for sure. OMG... the Spider, I bet it's still OEM too. I'll defiantly update after i'm done with the tune & cleaning. You know after that #3 plug on my 99' and doing the spider and lower intake gasket I was a bit relieved that I would't have to do them again after it got wreaked but here I am... Already replaced the plugs and probably gonna tackle the intake & spider again not to mention all the "typical 4x4" stuff I've just now been reading about here that I'm probably going to be running into. Glad the Mr.s gets 3 days off in a row every week, got a feeling i'm gonna be under the hood for the next month or so a bunch.

 

Yup Gotta LUV A blazer .... engineers dream - mechanics payday and can be a owners nightmare - LOL

 

I'm with odat, I wouldn't worry about those compression readings. Seems acceptable to me

 

You guys are probably right, did a block test and the block test passed. I tested the fuel psi at the service port, got 60psi but after 10 minutes it was down to 52psi. I haven't gotten underneath to test the pump or to see if psi is being lost at the tank, I'll do that tomorrow. Still haven't finished the full tune but seeing as my cyl#6 code just came back today and 52psi at the service port after 10min I wouldn't be surprised if the fuel tank & pump test fine.