Unsolvable?

frenchblue · 11-04-2009, 06:41 PM

My best friend has a 98 s10 2.2 auto. He loves the truck because it is bright red with stepside bed and etc. But he just cant figure out what is the matter with it(and neither can ANY mechanic within 20 miles).
It starts fine, but immediately starts loping. When he accelerates, the rpms continue to go up and down slightly and randomly even though he gives it steady throttle. It also has less power than any other s10 in the world, even the mechanics admit it is much weaker than any other 4 cyl s10 theyve ever driven. After exhausting every mechanic we knew of and most of his bank account on their "fixes", he was no better off than before. Finally i checked the vacuum and it was steady at 13. After a quick check of all the vac hoses, we were lost again. A mechanic said it must be internal failure, even though the engine makes no odd internal noises. A quick compression check brings up all cyl to be 130-140, which is perfect. So where is the vac going?
Then one day he decides to go old fashioned and get a bottle of soapy water and spray around the engine. The result: it bubbled when sprayed on the edge of the 4-pronged intake manifold(where it contacts the engine). Within seconds of spraying water on it, the bubbles disappear and the motor bogs down a little as if the water went straight through!
Now after changing the intake manifold gasket and then the entire intake manifold, the problem is unaffected. All the mechanics claim it isnt leaking there, but he has put a full tube of silicone around there and the truck runs, not perfectly, but def better.
So here he is, only a little better than at the start. Im sorry this got so long, but thanks for reading it(or skimming it) and please help us if you can.

GeorgesBlazah · 11-04-2009, 06:58 PM

Warped/cracked head?

frenchblue · 11-04-2009, 07:26 PM

he thought it would use coolant or at least lose compression if it was the head?

kc5gxc · 11-04-2009, 08:51 PM

Did he check the cat converter for plugging?
Pete

leroyme · 11-04-2009, 08:59 PM

The head or block being warped or cracked at the top would explain it. It might very well be leaking where the intake is in contact with it, making it run a little better when he put silicone on it. The mechanics would say it's not leaking because they changed the seal, but they cannot check to see if it is warped and making a good seal or not.

Good luck with it, man!

Bobthebiker · 11-04-2009, 09:13 PM

I'd do a leakdown test.

Frizman · 11-04-2009, 10:34 PM

Sounds to me that the head is cracked, and the only way to find out if it is or not is to take the head into a shop that can pressure check it. Which is more then what it would be worth to just put a new head on it. If you are looking for a cheap way to see if the head has a crack in it I would use some JB weld and put a layer on it. I am not saying this would be the best fix or if i am even right but that is the only explination it can be from the sounds of it that i can come up with.

SH-60B · 11-05-2009, 01:26 AM

Quote: Originally Posted by kc5gxc

Did he check the cat converter for plugging?
Pete

^ X1,000 A low vacuum with a lack of power are classic symtoms of exhaust blockage. Easy and free check, temporarily unbolt it, or take out the O2 sensor and re-check the vacuum, or test drive it to see if power is better.

frenchblue · 11-05-2009, 02:45 AM

He has actually had the exhaust system redone and it now has nothing more than a pair of straight-thru glasspack mufflers between the engine and tailpipe. One of the mechanics(chevy dealership) recommended adding a cat to "give it the backpressure it was designed to operate with", this resulted it quieter exhaust and slightly even weaker performance, as well as over $100 wasted to put one on and evenually have it removed again.

As for the cracked/warped head, we thought it should show other symptoms such as loss of coolant, milky oil, low compression, etc. So its possible for the top of the head to be warped/cracked where the manifold attaches without causing other symptoms? If so, he will have it checked out.

tg900 · 11-06-2009, 12:39 PM

hmm what about idle air control valve? just throwing it out there. My truck didn't want to run when mine went bad, and it only happened after it warmed up a bit. It would almost die when i tried to give it gas

nstoolman1 · 11-07-2009, 11:47 PM

If this was an older car with a distributor in it I would say you are describing, with the low vac., a possible timing issue. Check the timing. It's possible the computer is causing the timing to be retarted. I also am throwing ideas out.

eatinpavement · 11-08-2009, 02:27 PM

im thinking maybe a bad or leaky injector

frenchblue · 11-08-2009, 08:28 PM

tg900- the truck runs at idle and never has any prob with dying as far as i know. he did mention that if he really got on it hard for a few sec, it would try to die at idle and miss and lope worse at low rpms for a while, but would eventually straighten out in about 20 min or so.

nstoolman1- it is a 98 with coil packs....but from what ive read in repair manuals, if the map sensor picks up low vac., it will retard the ignition timing, thinking the truck is under heavy load.

eatinpavement- im pretty sure he has had gm to clean and flush the entire fuel system and check the injectors...but i think his main concern is the low vac.

he is agreeing with the possibility of a warped head. but he wants to make sure there would be no other symptoms that would point to a warped head...

slownlo · 11-08-2009, 08:31 PM

check your pcv I had the same damn thing. I was changing plugs one day and knocked it loose. just loose I could not hear it leaking it was just off a little and it caused my truck to surge while at idle and it had no power. I would definitely check it and all the other vacuum lines for faulty connection or a cracked hose. Remember its vacuum its not going to bubble its sucking not blowing. There is also a little filter looking thing in front of the motor on the passenger side it too will cause this if it is messed up. its near the thermistat, i think. I had that mess up on me years ago on my first s10.

frenchblue · 11-09-2009, 06:06 PM

ah yes. if we had a dollar for everytime a mechanic gave us the old "its vacuum so it wont cause bubbles" line, we'd just buy a lamborghini and call it a day.
Of course then there are things like: why does the soapy water only bubble when sprayed on that part of the intake manifold? and why does the engine have to be running for it to bubble or disappear? and why does the water disappear within 2 sec when sprayed there as opposed to 10-15 or more sec anywhere else? or why does the motor bog down a little right after the water disappears, then straightens out in a few secs, depending on how much water is sprayed? and what does putting a glob of silicone only where the water bubbles help the way it runs? Just unsolved mysteries i guess...
Then they would usually shrug their shoulders like i was speaking pig latin or something and suggest replacing something else that we had already checked or replaced...
As for the pcv valve, we looked the engine over and never could find one, so you might be thinking about the 94-97, but i dont think 98+ have one.

jraney · 11-09-2009, 06:50 PM

How many miles on it? Worn cam lobe? Did the vac increase when he put on the sealant?

slownlo · 11-09-2009, 10:47 PM

ah crap sorry never really messed around with the 98+. If the check engine light aint coming on its usually a pain to find out what it is. hope some one can help you guys out.

BarelyGettinBy · 11-09-2009, 11:05 PM

Im gonna say its a warped head. Open up the radiator and see if you have air bubbles in the coolant.

frenchblue · 11-10-2009, 01:10 AM

jraney- i think its got about 138,000. we figured it went up, but ive lost track of my vac gauge so we dont know for sure, just that it def runs better.

slownlo- thanks

barelygettinby- weve never noticed air bubbles, but one of the heater hoses busted open not long ago, which could mean too much pressure...but i dont know if it means anything or not.

Bobthebiker · 11-10-2009, 01:27 PM

for a radiator hose to burst from pressure, you would have to have a LOT of pressure assuming good condition hoses. and I mean a LOT. that coolant would first go through your overflow tank real easy, and bubble over from there.

I'm leaning toward warped head or headgasket now, so its time to bite the bullet and pull the head.

ls1s10onair · 11-10-2009, 02:04 PM

ok, ive breezed thru this thread quickly, and before pulling the head, id like to make a recommendation. With low vacuum, it is likely that you have a vacuum source with a bad diaphragm.... id suggest to put a vacuum gauge on it, and pull the brake booster hose off, and block it with ur finger. if the booster is going, or the check valve is bad, the booster can be using up your vacuum supply... if the gauge goes up, youve found ur problem. this can be done with any vacuum source, cuz it isnt uncommon. As for the heater hose, there is a good enough chance that was caused from age, and not compression in the coolant. Before pulling the head, make sure the coolant is full, and the engine is cold.... with the cap off, start the engine, and check to see if the coolant either shoots upward, or immediately spills over (a lot)... thats a little easier than pulling a cylinder head that may or may not be the problem

frenchblue · 11-10-2009, 05:00 PM

The brake booster hose was the one we used to check the vacuum, so if the booster was leaking, it wouldnt have showed up.
So i guess we'll just check the coolant and/or pull the head and replace it, if he wants to put that much more money into it. Thanks guys.

11-04-2009, 06:41 PM	#1
frenchblue Registered User Join Date: Sep 2009 Posts: 34 Location: User is: OffLine	Unsolvable? My best friend has a 98 s10 2.2 auto. He loves the truck because it is bright red with stepside bed and etc. But he just cant figure out what is the matter with it(and neither can ANY mechanic within 20 miles). It starts fine, but immediately starts loping. When he accelerates, the rpms continue to go up and down slightly and randomly even though he gives it steady throttle. It also has less power than any other s10 in the world, even the mechanics admit it is much weaker than any other 4 cyl s10 theyve ever driven. After exhausting every mechanic we knew of and most of his bank account on their "fixes", he was no better off than before. Finally i checked the vacuum and it was steady at 13. After a quick check of all the vac hoses, we were lost again. A mechanic said it must be internal failure, even though the engine makes no odd internal noises. A quick compression check brings up all cyl to be 130-140, which is perfect. So where is the vac going? Then one day he decides to go old fashioned and get a bottle of soapy water and spray around the engine. The result: it bubbled when sprayed on the edge of the 4-pronged intake manifold(where it contacts the engine). Within seconds of spraying water on it, the bubbles disappear and the motor bogs down a little as if the water went straight through! Now after changing the intake manifold gasket and then the entire intake manifold, the problem is unaffected. All the mechanics claim it isnt leaking there, but he has put a full tube of silicone around there and the truck runs, not perfectly, but def better. So here he is, only a little better than at the start. Im sorry this got so long, but thanks for reading it(or skimming it) and please help us if you can.
	[Reply w/Quote]

11-04-2009, 06:58 PM	#2
GeorgesBlazah Slap my meat on your pita Age: 24 Join Date: Sep 2004 Posts: 7,215 Location: south jersey User is: OffLine	Re: Unsolvable? Warped/cracked head?
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11-04-2009, 07:26 PM	#3
frenchblue Registered User Join Date: Sep 2009 Posts: 34 Location: User is: OffLine	Re: Unsolvable? he thought it would use coolant or at least lose compression if it was the head?
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11-04-2009, 08:51 PM	#4
kc5gxc Registered User Join Date: May 2005 Posts: 52 Location: User is: OffLine	Re: Unsolvable? Did he check the cat converter for plugging? Pete
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11-04-2009, 08:59 PM	#5
leroyme Half-Bagged for now Age: 29 Join Date: Jan 2004 Posts: 1,632 Location: Wichita, KS User is: OffLine	Re: Unsolvable? The head or block being warped or cracked at the top would explain it. It might very well be leaking where the intake is in contact with it, making it run a little better when he put silicone on it. The mechanics would say it's not leaking because they changed the seal, but they cannot check to see if it is warped and making a good seal or not. Good luck with it, man!
	[Reply w/Quote]

11-04-2009, 09:13 PM	#6
Bobthebiker Registered User Age: 21 Join Date: Aug 2009 Posts: 573 Location: User is: OffLine	Re: Unsolvable? I'd do a leakdown test.
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11-04-2009, 10:34 PM	#7
Frizman Registered User Age: 23 Join Date: Dec 2008 Posts: 22 Location: User is: OffLine	Re: Unsolvable? Sounds to me that the head is cracked, and the only way to find out if it is or not is to take the head into a shop that can pressure check it. Which is more then what it would be worth to just put a new head on it. If you are looking for a cheap way to see if the head has a crack in it I would use some JB weld and put a layer on it. I am not saying this would be the best fix or if i am even right but that is the only explination it can be from the sounds of it that i can come up with.
	[Reply w/Quote]

11-05-2009, 01:26 AM	#8
SH-60B Registered Neanderthal Join Date: Nov 2007 Posts: 2,335 Location: Meriden/CT/USA User is: OffLine	Re: Unsolvable? Quote: Originally Posted by kc5gxc Did he check the cat converter for plugging? Pete ^ X1,000 A low vacuum with a lack of power are classic symtoms of exhaust blockage. Easy and free check, temporarily unbolt it, or take out the O2 sensor and re-check the vacuum, or test drive it to see if power is better. Last edited by SH-60B : 11-05-2009 at 01:34 AM.
	[Reply w/Quote]

11-05-2009, 02:45 AM	#9
frenchblue Registered User Join Date: Sep 2009 Posts: 34 Location: User is: OffLine	Re: Unsolvable? He has actually had the exhaust system redone and it now has nothing more than a pair of straight-thru glasspack mufflers between the engine and tailpipe. One of the mechanics(chevy dealership) recommended adding a cat to "give it the backpressure it was designed to operate with", this resulted it quieter exhaust and slightly even weaker performance, as well as over $100 wasted to put one on and evenually have it removed again. As for the cracked/warped head, we thought it should show other symptoms such as loss of coolant, milky oil, low compression, etc. So its possible for the top of the head to be warped/cracked where the manifold attaches without causing other symptoms? If so, he will have it checked out.
	[Reply w/Quote]

11-06-2009, 12:39 PM	#10
tg900 Dialed! Age: 22 Join Date: May 2006 Posts: 734 Location: PA User is: OffLine	Re: Unsolvable? hmm what about idle air control valve? just throwing it out there. My truck didn't want to run when mine went bad, and it only happened after it warmed up a bit. It would almost die when i tried to give it gas
	[Reply w/Quote]

11-07-2009, 11:47 PM	#11
nstoolman1 Registered User Join Date: Sep 2007 Posts: 112 Location: Southern California User is: OffLine	Re: Unsolvable? If this was an older car with a distributor in it I would say you are describing, with the low vac., a possible timing issue. Check the timing. It's possible the computer is causing the timing to be retarted. I also am throwing ideas out.
	[Reply w/Quote]

11-08-2009, 02:27 PM	#12
eatinpavement Registered User Age: 30 Join Date: Jul 2008 Posts: 100 Location: User is: OffLine	Re: Unsolvable? im thinking maybe a bad or leaky injector
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11-08-2009, 08:28 PM	#13
frenchblue Registered User Join Date: Sep 2009 Posts: 34 Location: User is: OffLine	Re: Unsolvable? tg900- the truck runs at idle and never has any prob with dying as far as i know. he did mention that if he really got on it hard for a few sec, it would try to die at idle and miss and lope worse at low rpms for a while, but would eventually straighten out in about 20 min or so. nstoolman1- it is a 98 with coil packs....but from what ive read in repair manuals, if the map sensor picks up low vac., it will retard the ignition timing, thinking the truck is under heavy load. eatinpavement- im pretty sure he has had gm to clean and flush the entire fuel system and check the injectors...but i think his main concern is the low vac. he is agreeing with the possibility of a warped head. but he wants to make sure there would be no other symptoms that would point to a warped head...
	[Reply w/Quote]

11-08-2009, 08:31 PM	#14
slownlo built for stangs Age: 28 Join Date: Jun 2004 Posts: 182 Location: orlando fl User is: OffLine	Re: Unsolvable? check your pcv I had the same damn thing. I was changing plugs one day and knocked it loose. just loose I could not hear it leaking it was just off a little and it caused my truck to surge while at idle and it had no power. I would definitely check it and all the other vacuum lines for faulty connection or a cracked hose. Remember its vacuum its not going to bubble its sucking not blowing. There is also a little filter looking thing in front of the motor on the passenger side it too will cause this if it is messed up. its near the thermistat, i think. I had that mess up on me years ago on my first s10.
	[Reply w/Quote]

11-09-2009, 06:06 PM	#15
frenchblue Registered User Join Date: Sep 2009 Posts: 34 Location: User is: OffLine	Re: Unsolvable? ah yes. if we had a dollar for everytime a mechanic gave us the old "its vacuum so it wont cause bubbles" line, we'd just buy a lamborghini and call it a day. Of course then there are things like: why does the soapy water only bubble when sprayed on that part of the intake manifold? and why does the engine have to be running for it to bubble or disappear? and why does the water disappear within 2 sec when sprayed there as opposed to 10-15 or more sec anywhere else? or why does the motor bog down a little right after the water disappears, then straightens out in a few secs, depending on how much water is sprayed? and what does putting a glob of silicone only where the water bubbles help the way it runs? Just unsolved mysteries i guess... Then they would usually shrug their shoulders like i was speaking pig latin or something and suggest replacing something else that we had already checked or replaced... As for the pcv valve, we looked the engine over and never could find one, so you might be thinking about the 94-97, but i dont think 98+ have one.
	[Reply w/Quote]

11-09-2009, 06:50 PM	#16
jraney Registered User Age: 51 Join Date: May 2009 Posts: 67 Location: NNJ User is: OffLine	Re: Unsolvable? How many miles on it? Worn cam lobe? Did the vac increase when he put on the sealant?
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11-09-2009, 10:47 PM	#17
slownlo built for stangs Age: 28 Join Date: Jun 2004 Posts: 182 Location: orlando fl User is: OffLine	Re: Unsolvable? ah crap sorry never really messed around with the 98+. If the check engine light aint coming on its usually a pain to find out what it is. hope some one can help you guys out.
	[Reply w/Quote]

11-09-2009, 11:05 PM	#18
BarelyGettinBy Registered User Age: 20 Join Date: Apr 2008 Posts: 1,359 Location: London Ky User is: OffLine	Re: Unsolvable? Im gonna say its a warped head. Open up the radiator and see if you have air bubbles in the coolant.
	[Reply w/Quote]

11-10-2009, 01:10 AM	#19
frenchblue Registered User Join Date: Sep 2009 Posts: 34 Location: User is: OffLine	Re: Unsolvable? jraney- i think its got about 138,000. we figured it went up, but ive lost track of my vac gauge so we dont know for sure, just that it def runs better. slownlo- thanks barelygettinby- weve never noticed air bubbles, but one of the heater hoses busted open not long ago, which could mean too much pressure...but i dont know if it means anything or not.
	[Reply w/Quote]

11-10-2009, 01:27 PM	#20
Bobthebiker Registered User Age: 21 Join Date: Aug 2009 Posts: 573 Location: User is: OffLine	Re: Unsolvable? for a radiator hose to burst from pressure, you would have to have a LOT of pressure assuming good condition hoses. and I mean a LOT. that coolant would first go through your overflow tank real easy, and bubble over from there. I'm leaning toward warped head or headgasket now, so its time to bite the bullet and pull the head.
	[Reply w/Quote]

11-10-2009, 02:04 PM	#21
ls1s10onair Local Tech Age: 26 Join Date: Jan 2008 Posts: 3,242 Location: westwood, nj User is: OffLine	Re: Unsolvable? ok, ive breezed thru this thread quickly, and before pulling the head, id like to make a recommendation. With low vacuum, it is likely that you have a vacuum source with a bad diaphragm.... id suggest to put a vacuum gauge on it, and pull the brake booster hose off, and block it with ur finger. if the booster is going, or the check valve is bad, the booster can be using up your vacuum supply... if the gauge goes up, youve found ur problem. this can be done with any vacuum source, cuz it isnt uncommon. As for the heater hose, there is a good enough chance that was caused from age, and not compression in the coolant. Before pulling the head, make sure the coolant is full, and the engine is cold.... with the cap off, start the engine, and check to see if the coolant either shoots upward, or immediately spills over (a lot)... thats a little easier than pulling a cylinder head that may or may not be the problem
	[Reply w/Quote]

11-10-2009, 05:00 PM	#22
frenchblue Registered User Join Date: Sep 2009 Posts: 34 Location: User is: OffLine	Re: Unsolvable? The brake booster hose was the one we used to check the vacuum, so if the booster was leaking, it wouldnt have showed up. So i guess we'll just check the coolant and/or pull the head and replace it, if he wants to put that much more money into it. Thanks guys.
	[Reply w/Quote]