A weird smell and water or gas out of the Pipes

I just recently replaced the thermostat and after i cranked it up it started to smell like either sewer or something terible i can't describe it and i'm almost positive it was coming from the truck but when i was revving it it started shooting out either gas or water from the tail pipes i couldn't tell it was in a field and i've been getting terrible gas mileage i put in about $30.00 in gas and got about 100 miles out of it. I've put in a good synthetic replaced alot of the filters pcv valve alot of stuff i've only had it about 1 month its an 88 350 any help would be appreciated its just not running like when i bought it. Thanks

is the rad full? and is the engine coolant sensor plugged in?

yeah its completley full and connected i'm almost positive its not that

Any other comments

Water out the tailpipe is normal. The hyrdocarbons in the gas combine during combustion to make H2O. For every gallon of gas burned, 1 gallon of water is produced. If it's pouring out, some of it is probably unburned gas. You could collect a sample of it and see if it will burn. If it does, there is WAY TOO MUCH gas in it.

How long since a tuneup? Hitting on all cylinders?

It had a tune up one month ago i did it just after i bought it i've been reading some on the forum and i'm thinking its the Catalytic Converter I think i'm just going to saw it off and put a straight type until i can afford a high flow one. Would my gas mileage be better with it off and what about power its a 1988 with 175000 miles on it any info would be appreciated thanks

It had a tune up one month ago i did it just after i bought it i've been reading some on the forum and i'm thinking its the Catalytic Converter I think i'm just going to saw it off and put a straight type until i can afford a high flow one. Would my gas mileage be better with it off and what about power its a 1988 with 175000 miles on it any info would be appreciated thanks

I was gettin ready to suggest its probably your converter stopped up. By taking it off, you will notice an increase in power, however you'll loose back pressure and this will evcentually get the valves.

Also, your truck will be louder then LOUD with straight pipes, so don't be suprised if you get pulled everytime you meet/see a cop.

Have you drivin the truck after you changed the thermostat? Just wondering if the smell is indeed coming from your truck or possibly just something near where you parked. If it is in fact coming from your truck, does it have more like a rotten egg type smell? If so, 99.9% sure it is your catalytic converter. Don't have the scientific reason like J-Ri, burt he is right that water in the tail pipe is common. I just always thought it was condensation. Guess we do learn something everyday!

I was looking at the converter and it was bolted on so i assume it has been replaced since it wasn't welded so then i thought to check the o2 sensor and we worked on it for about 1 hour but we couldn't get it to budge any tips on removing this and could it be the problem thanks

LOTS and LOTS of penetrating oil...

The O2 sensor could be part of the problem. You may have to heat it up to free the O2 sensor. Either let it run for a while or carefully use a torch. Should come out then. make sure to use anti-seize lube on the new one.

Have you drivin the truck after you changed the thermostat? Just wondering if the smell is indeed coming from your truck or possibly just something near where you parked. If it is in fact coming from your truck, does it have more like a rotten egg type smell? If so, 99.9% sure it is your catalytic converter. Don't have the scientific reason like J-Ri, burt he is right that water in the tail pipe is common. I just always thought it was condensation. Guess we do learn something everyday!


I just changed my O2 sensor last week. I have a 91 1500 and that was the original rusty sensor. What I did to get it off was to drive the truck until the pipe was really hot then I hit it with a good dose of PB Blaster and waited about 10 or 15 minutes. Remember to put on gloves before you try to wrench it off..... I Used an adjustable wrench and put some weight on it and it spun right off. Also if you havent done so already, check your EGR valve. The diaphram inside of it might not be holding vacuum, mine was shot too and cost about $55 bucks to replace. I would suggest you check all the vacuum lines to make sure they are not leaking and check the flow out of the injectors to make sure they are not spraying unevenly. If they are they might be clogged or the fuel pressure regulator might be in need of a rebuild. The pain in the ass about all computer controlled vehicals is one sensor can confuse the hell out of the computer. I have been trying to pass inspection on my truck for the past 2 weeks and it is costing me a small fortune in parts my HC was 4.30 and it should be 1.60 I am almost done and the exhaust is smelling so much better now.

I finally got it off i had to break it off to allow an exact socket to fit over the nut then i put a big pipe over the wrench and got it that way when i got it out it was green does that mean anything but the new one i put in wouldn't screw in all the way i got it as close as i could but it wouldn't go any further would that hurt its readings at all it needs about 3 more full turns i felt down there and i don't think its leaking any air but any more info would be appreciated thanks

If it didn't go on easily, there is a good posability that it didn't seal properly which I would think could affect the readings since there would be an "exhaust leak"-even though it would be very minor, it would still be an "exhaust leak" which might even effect back pressure.

the cat on all early gm trucks were bolted on. if its about 2 1/2 - 3 ft long and about 2 ft wide, then its probable the factory cat. or atleast replaced with afactory one, dosent sound like it though. i drive an 87 with 223,000 plus miles on it and i took my cat off about 4 years ago. i havent had any probs with it yet, and if you have any type of aftermarket muffler on it it will be considerably louder. one good way to tell if its cloged is to drive it, if it feels like it just wouldent get out of its own way if it fell off a cliff then it may be cloged.

Yeah its probably stock then i'm going to go have it checked by a muffler shop next week. I would take it off if i knew for sure that it wouldn't hurt the valve seals like one person said in an earlier post does someone know if that would happen i think there already a little bit bad thanks

Yeah its probably stock then i'm going to go have it checked by a muffler shop next week. I would take it off if i knew for sure that it wouldn't hurt the valve seals like one person said in an earlier post does someone know if that would happen i think there already a little bit bad thanks

Its not the valve stem seals, its the vavles that it will get. You'll loose back pressure when you take the cat off and it will eventually burn the valves up...however it probably would take a long time for this to happen, but it will happen.

If it was me, I'd get a new converter for it, but only becuase I despise the way those trucks sound without one (even with an aftermarket muffler).