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1999 GMC Yukon, Help Please!!!
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HangtownYukon
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Nov 3, 2011, 9:26 PM
Post #1 of 13
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1999 GMC Yukon, Help Please!!!
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To all of those that have given your heart and soul, skinned knuckls and broken backs to your trade:
I have a 1999 GMC Yukon 4 door 5 liter 350 engime 4WD SLT with 75, 750 miles on it. This vehicle has been pampered, and looks showroom new, and every underwriter that has ever taken a work order on it solicites to buy it should we ever wish to sell it. It has never been off road, and we only drive it occasionally but are religous in maintenance. O.K. Here is my dilema, and I pray you all have the answer. On three occaisions starting last year in the heat of the summer, while driving up a gradual grade from 100 foot elevation to 1800 feet, the engine has bogged, lost power, and the check engine light goes on. This loss of power lasts only a few seconds, however the engine light stays on. The dealer could not recover the code the first time, but replaced the fuel injection system (tipet isues) but to no avail. Two other occaisions revealed according to the dealer an issue with cylinder head 4 or 5, stating that the exhaust valve is getting stuck. I contacted a techy at Edelbrock who has two 96/99 vehicles and siad that that this was was manufacturer problem, where the exhasut valve has improper clearance and gets stuck momentarily. He said that have corrected it by increasing the circumfrance of the exhaust.
Here is my dilemna. The dealer wants to perform a valve job on both heads, having the heads machine at a machine shop, and then replacing the now rebuilt heads on my vehicle at the cost of approximately $2300.00. The techy at Edelbrock gave me the idea of ordering a new set of aluminum heads fro G.M. (factory replacement) at the cost of $330 per head, and then just swapping my current items (springs, rockers etc) off my old heads onto my new heads, thus saving the cost of machining my old heads.
The vehicle runs great except for these three occaisions. Now I humbly pray to you Doctors of grease and school of achy backs for your advice on what to do. Yes, $2300.00 is alot to spend on a vehicle with only 75K miles on it, however we plan on keeping it, and do not want to risk major engine damage if we do not fix this issue. I really appreciatte your feedback. The new factory replacement heads would only work out to a couple of hundred bucks more given the machine shop time saved. God bless all you under appreciatted grease monkeys! Thanks-Steve
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Sidom
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Nov 3, 2011, 10:43 PM
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Re: 1999 GMC Yukon, Help Please!!!
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Well looks like you've covered a couple of the common problems, they have a lot of problems with their fuel systems & those are prone for valves sticking. If you haven't changed the fuel pump yet, I'd put that in the budget as well
If you're planning on keeping it & the price is close there is no question you should use the new heads, even if the price wasn't so close, by the way you've been maintaining this the new heads would be the best options...
What codes was this throwing???? Misfire & lean codes???
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Tom Greenleaf
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Nov 3, 2011, 11:36 PM
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Re: 1999 GMC Yukon, Help Please!!!
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What engine is in this? 5.0 is 305 CID and 5.7 is the 350. R (if so) code engines like strong fuel pumps~ 58-62. If lower they mess up or don't run or start well or not at all. Why mess with Edelbrock? IMO that stuff is for Hot Rod stuff from ages ago,
T
(This post was edited by Tom Greenleaf on Nov 3, 2011, 11:40 PM)
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Hammer Time
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Nov 4, 2011, 10:08 AM
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Re: 1999 GMC Yukon, Help Please!!!
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Hangtown..... I deleted your empty post. Try again
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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HangtownYukon
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Nov 4, 2011, 10:30 AM
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Re: 1999 GMC Yukon, Help Please!!!
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Dear Tom and Sidom,
No code showed from the dealer, however that stated "It is possible that #5 cylinder valves are hanging intermitantly in valve guides". I had the fule pump replaced and new fuel assembly with air flow senser cleaned. As this has happened 2 or three times in two years, and lasted 3 secinds, is it neccessary to spend near three thousand to redo both heads with just 75 K on the engine. The vehicle drives like a dream since. I am recovering from a 16 year old kid rear ending me earlier this year and am on disability after undergoing major spinal reconstruction in my neck 6 weeks ago, and every penny is tight, not to mention now dealing with steel rods, screws and titanium plates in my neck, pain that would bring the toughest dude to tears, and double questioning every financial decision I make. Is there an additive that I could use to avoid future the valve from sticking instead, or am I taking the wrong road. I want to make sure that I do the right thing before causing more harm to the engine (pennywise, pound foolish as they say).
On another note, I just replaced all four tires from Cooper tires (many defects experienced with these "tires" with B.F. Goodrich all terrains yesterday (more in debt) but am very pleased with the B.F.'s. So I am not refusing to spend the money in needed, I just dont want to make the dealer's next cadillac payment if I do not need to. Once again, thanks guys! God Bless.
Steve
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Tom Greenleaf
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Nov 4, 2011, 12:49 PM
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Re: 1999 GMC Yukon, Help Please!!!
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Steve,
From memory of first post now as I'm not having two windows open to look back and forth here. The only engine available (listings can be wrong) was the 5.7 (350 C.I.D) Vortec that comes with cast iron heads. Just checked my own 1997 to be certain.
Two quirks well known are intake manifold gaskets AND they must have proper fuel pressure for forget it. Aftermarket fuel pump have a terrible failure rate. Other which doesn't seem to be the case with yours is rust. My O2 sensors rusted the cap that holds the wires to them - one fell right off! Did them all (four) dammit.
What's with Edelbrock? Why? Are the heads different now that OE and why? Why with especially a check engine light on couldn't a dealer isolate which cylinder and just guess #4or5?
I've pretty much never heard of needing a valve job on a cared for small block real Chev engine at low miles? OK - GM screwed up with a couple things but so far never heard of the valves unless something happened. Changing to alloy heads is like Russian Roulette with all six bullets IMO. One good overheat with dissimilar metals and you are back to doing it all over again.
Dealer couldn't pull hard codes! Nothing of any certainty? That doesn't jive.
You may have said so but is this making "sticky lifter" type noise? Rare to me but one other thing on this block that dates back to the Civil War is cam lobes can wear but wouldn't be intermittent. Fuel pressure could and I've fought with one. You hear the complaint and it all checks out then ah-ha, caught it in the act! Rust belt cars have reported some problems with the connection right at the pump but none w me not surprising as I'm retired and don't see more than a few different family cars locally and tons of my own. I hear about many and read about tons right here.
For now check fuel pressure and probably do fuel filter no matter how new it is. Any (well most) OBDII vehicles if not running well for more than a few seconds are going to set off codes. If light went on it did. Perhaps a second opinion?
Tom
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HangtownYukon
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Nov 4, 2011, 10:37 PM
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Re: 1999 GMC Yukon, Help Please!!!
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HeyTom,
I had the intake manifold replaced, new fuel pump, new fuel filters, new fuel injector system, new brake master cylinder, new steering unit. steering box/rod, new transaxle seal, seems like new everything. The factory heads are aluminum, which is what came new iwth the 5.7 liter 350 engine new. The story I have heard is that the valve guides in the original heads were a little too tight as a manufacturer issue. What the dealer is suggesting is haveing the original heads machined to open that valve clearance up, or ordering a new set of factory G.M. heads, and just swapping over the exisiting springs, valaves etc. The new heads availible from the factory have that clearance issue already rectified. My big question is why spend 2500-3000 grand for a complete valve job for two isolated incidents when the only audible sounds was a three second bog, a slight loss of power, and then nothing else? No lifter sounds, nada. The car runs great except in 100 degree weather, climbing a steep hill, and this happened only twice. Is there an additive I could use for this issue?
My fear that the dealer instilled into my paranoia is that we could suffer major engine damage if the exhaust vlave stuck in a like situation. The car has 75K on it, engine oil changed @ 3k miles, has an engine compartment that is cleaner than most dishes or utensils at your average restaurant, and it purrs all the rest of the time. I'll spend the money if needed (on credit) but I feel I am getting railroaded by the service underwriter. What say you? Thanks for your input Buddy!
Steve
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Tom Greenleaf
Ultimate Carjunky
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Nov 4, 2011, 11:40 PM
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You said ">>My big question is why spend 2500-3000 grand for a complete valve job for two isolated incidents when the only audible sounds was a three second bog, a slight loss of power, and then nothing else? No lifter sounds, nada.<<"
Computer controlled as the truck is for a couple isolated 3 second things like that I'd forgive and forget it. If it was happening with some regularity or always at higher outside temps then I'd be concerned. 100F is NOT all that extreme IMO unless pulling a severe load up hill w weak fan clutch that's nothing.
I'll check my own 5.7 about the heads. A '96 Suburban is one I tend to also and a family member owns a '99 that isn't near me but has tons of miles and no issues.
Your call but my new fav oil is Mobil 1, 0-30! You'd think it too light for higher temps but magically isn't. Claims meets or exceeds all specs for 5-30 or 10-30. Holds great oil pressure at idle on a hot day as well as any and it amazes me. Synthetics tolerate heat and cold much better than conventional which should be fine if still tended to. I swear the synthetics keep sludge to near zero longer - a huge enemy and will clean up varnish and existing reasonable sludge better than others. Forget additives just take care of it on time + miles. Temp gauge shouldn't move once up to temp or tend to that - weak fan clutch or radiator possible if it does.
I still don't get it with the advice from the dealer who has this in front of them which beats this on line stuff which helps, but nothing like being there.
Good luck. I don't mean to beat on the dealer but the "associative properties of addition" of not being able to pull codes AND make $3000 buck suggestions makes me wonder,
T
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Sidom
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Nov 5, 2011, 11:59 AM
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Re: 1999 GMC Yukon, Help Please!!!
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Tom pretty much covered the bases on oiling & cooling. Synthetics are good but as Tom pointed out the correct weight is critical. Go with what ever it calls for. You see some guys wanting to run 20-50w "cuz that's what they've always used in their sb chevys" and that's a killer.
As far as bending valves, normally you see that with a mechanical failure. It jumped time & you have a cam lobe "holding" that valve open at the wrong time and the piston hits it. This is just a case of varnish & carbon causing a sticking problem in a valve guide, not hard mechanical part. So if that was the case, you would've already bent a valve, 2 or 3 times ago.
Flushing is good as long as the mileage isn't too high with excessive sludge build up, then it wouldn't be a good idea. but with the valve seals you really aren't going to get alot of the cleaner in the guides, mainly just cleaning off the stems. Fuel system cleaning also helps. It will take the deposits off the valves & clean the pistons, which can help prevent further problems. There are a few different services out there that are all called "injection cleaning" but not all do the same. You want to get a shop the will run the cleaner thru the injectors via full system as well as running a cleaner thru the intake system.
I'm not real big on running additives, if normal maintenance is kept up then they really aren't needed. I know Seafoam is a pretty good product. I've seen guys use that will some pretty good results. You could google it & read up on it & see what you think about it...
As far as a professional injection service. BWD (Borg Warner) makes a good cleaner I like. BG makes really good products but I haven't had a chance to use them much. I would say the MOC makes the best cleaner I have personally used. A little more expensive but worth it. It was too bad the shop dropped the line....
I had thought by your original post you had already decided on doing the job & were just looking at the different opinions. Since you are still debating and this has only happened a few times I would probably start off with flushing the engine & fuel service, go with a good grade of gas, every once & a while run some injection cleaner when filling up and see if that makes any difference for you.......
(This post was edited by Sidom on Nov 5, 2011, 12:00 PM)
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Tom Greenleaf
Ultimate Carjunky
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Nov 5, 2011, 1:21 PM
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Sidom - Check out that Mobil 1 .......... 0-30. Said that I was shocked that oil pressure stays up there. It just starts in lawn mower and vehicles so much better than even 5-30? Dunno why but it claims to (always doubt stuff) but it holds it's range. When warm it behaves like the 30 weight as that's the idea.
Absolutely noticed in a 12.5 HP mower right away easier to pull start and doesn't burn it?
Probably already said here or somewhere. Bought a car with known sticking valves and sludge but body and interior were so awesome I took it. Nothing but overdoing oil changes (always Mobil 1 something) cleaned it up! Took a year but no ticking at all even cold starts, fast to put oil idiot light out and dang car went on way up there in miles after me and may still be out there. I don't believe in much magic but I lived it and saw it work on ordinary sticking lifters and probably valve guides too and won't know as it plain self corrected which may have been just luck or did the oil really do it? Can it fix real mechanical anything - of course not,
T
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HangtownYukon
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Nov 5, 2011, 9:01 PM
Post #11 of 13
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Sidom and Tom,
The issue according to the dealer was improper valve cleareance in the heads, regardless, thanks for your input. Me thinks I'll save getting more in debt, and use the Mobil tonic, and at the same time, perhaps order one shaken, and not stirred, maybe once I recover from my spinal surgery, I'll see if this libation can add 12. horses below the belt and patent this miracle cure, to put viagra out of business, who knows, you may tune in one late night, and see me surrounded by buximess beauties bragging about "added performance from this old machine" and to think, I owed it to the both of you, vroom-vroom. Seriously, thanksguys!
Steveus-Mobilis Uno. (latin for yours truely)
Steve aka Hangtownyukon
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Sidom
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Nov 5, 2011, 9:22 PM
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You should be good.
Good luck with everything, hope the health issues work out for you & when you hit it big......Don't forget us little guys..
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Tom Greenleaf
Ultimate Carjunky
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Nov 6, 2011, 6:11 AM
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Re: 1999 GMC Yukon, Help Please!!!
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Steve - Thanks for posting the fix and good luck with the surgery. Seems too many friends have been there and ALL came out great!
Mobil 1 - Laugh, been using it since it was in a silver metal can only sold as 5-20! They used to advertise showing poured into a red hot fry pan and it didn't cake up where conventional did. Got sued bad for saying you can leave it in for 25,000 miles - NOT! Change like any other oil.
Be well,
Tom
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