Help me fix my turd blazer motor over heats

[nsxxtreme]

So my blazer started having issues lately. Originally it would run fine and then start to lose power then die. I thought maybe it needed a new distributor cap. So I replaced that and the spark plugs. It ran better then started doing the same thing.

I'm fairly sure this is an ignition problem because I can smell the fuel when it does this. Next I replaced the entire ditributor. Today while towing the boat it did fine until a hill. I started to lose power and then it misfired a few times. Eventually it over heated and I had to pull over.

All I can think of at this point is the coil. So I bought a new coil and will replace it tomorrow.

My check engine light also comes on after driving a while but I have no way of reading the codes. Any other ideas?

 

[ryoken]

first, vehicle specs would help.... is this carb or tbi?

just because you "smelled fuel" doesn't mean that isn't the issue... as a matter of fact, it inclines me to believe it probably has a flooding issue and your getting too much.... how did the plugs look?

you can check codes with a paper clip.. i would do that first..

http://www.troublecodes.net/GM/

 

[nsxxtreme]

first, vehicle specs would help.... is this carb or tbi?

just because you "smelled fuel" doesn't mean that isn't the issue... as a matter of fact, it inclines me to believe it probably has a flooding issue and your getting too much.... how did the plugs look?

you can check codes with a paper clip.. i would do that first..

http://www.troublecodes.net/GM/

TBI it is running extremely rich right now.

 

[Confedneck]

overheating and running rich?

 

[nsxxtreme]

overheating and running rich?

Yes....Just checked the EGR valve and its not good but it looks to be stuck closed not open.

So I replaced the EGR and now at tip in from idle I can feel pressure coming back up through the TBI.
I am assuming that is related to the EGR valve. I dont know much about these cars so any help is appreciated.

Still seems to run rough. I checked the valves on one side also and they seem to be ok.

 

[garlicbreath]

Can you separate the two problems? IE work on the over heating first, then diagnose the rest? I've heard of an engine running way lean overheating, but not rich.


Can you swap motors out first to solve the overheating?

 

[nsxxtreme]

Can you separate the two problems? IE work on the over heating first, then diagnose the rest? I've heard of an engine running way lean overheating, but not rich.


Can you swap motors out first to solve the overheating?

It could have just overheated because I was towing my boat up hill and it was running like crap.

I pulled the plugs and they are black its running very rich and knocking very easily under load. I tried playing with the timing but no luck

Broken rings maybe? How do I test for that?

 

[nsxxtreme]

you can check codes with a paper clip.. i would do that first..

http://www.troublecodes.net/GM/

None of those match my 87 TBI 5.7L

Closest I could find was the 89 and a code of 13 I think has someing to do with the oxygen sensor sensing a rich signal. I replaced the 02 sensor it had been laying up against the header and melted the wire. Still runs like crap though.

 

[crawlink5]

I had a 305 tbi do that. The hose between the fuel pump and the line inside the gas tank had a hole in it so there wasn't enough pressure. The injectors would open wide open while driving because the engine though it was not getting enough fuel so open up to get more. As soon as I slowed down the ecm didn't close the injectors quick enough and would flood the engine.

Sounds strange but that was the issue found it when I went to change the pump. May not be your problem.

If you washed your engine recently then change your tps

 

[nsxxtreme]

Problem solved, Blown head gasket. Cylinders 3&5 leak between each other. I did a leak down test on all the other cylinders and they seem to be ok. The leak between 3&5 is huge no compression at all on those cylinders and if you pressurize one the air comes out the spark plug of the other.

Now the bigger question is what causes the head gasket to blow? Yes it over heated but only after it lost power and I kept pushing it to get it off the freeway.

The symptoms were it was running strong then approached a big hill started out fine then progessivly started to lose power until just about all power was gone. This motor is about a year old and maybe 5-10k miles on it.

I have yet to pull the heads but have already pulled the motor and its on an engine stand. Heads will probably be removed tomorrow.

 

[Greg72]

Looks like you'd better fast track that 383 build you started....

Not to pour salt on an open wound, but how confident are you in your engine building abilities? You rebuilt that 350 yourself not too long ago, and now it's toast. Building a 383 is going to be expensive enough. It might be worth having an experienced machinist do all the assembly just to make sure you don't end up with even more issues on the next motor.

 

[nsxxtreme]

Looks like you'd better fast track that 383 build you started....

Not to pour salt on an open wound, but how confident are you in your engine building abilities? You rebuilt that 350 yourself not too long ago, and now it's toast. Building a 383 is going to be expensive enough. It might be worth having an experienced machinist do all the assembly just to make sure you don't end up with even more issues on the next motor.

That motor should have never been rebuilt to begin with. I listened to other people who were american car guys and they thought it would be enough that is where I think it went wrong. That motor is a turd and never had anywhere near enough power to tow a boat with 35" tires. Heck I would venture to say that motor is barely adequate to push the blazer itself around. Maybe I just expected to much out of it. I found the difference between the American car guys and other people is dropping into second and doing 35 up a hill on the freeway is completely acceptable to them. Then I hear abought be sure to buy American parts, such as vortec heads. Then you find out from machine shops 90% of them come in cracked. So much for American quality. The positive is that parts are so damn cheap its like rebuilding a lawn mower.

The head gasket for this motor will be replaced and put into someone elses truck. They can do the 35 mph thing its just not for me. Nothing is wrong with the motor except the head gasket and I used Felpro gaskets. My sisters V6 4 runner made it up the hill fully loaded with 5 adults towing my boat doing 65 mph no problem. Kinda pathetic really. The emission control crap they put on these 80's early 90's motors made these motor junk IMO. 220hp out of a V8 come ON!! You gotta admit that is pretty pathetic. From what I understand the stock TBI can only flow somewhere around 400 cfm without modification. And even then the max is 600 cfm still pretty weak.

The decision to put a 383 in was decided before this motor decided to give up. This just expedited the process. The stock TBI will be junked and I'll be going with a BB TBI. Plus what fun is it if you pay someone to do everything for you? To many people are to damn lazy or to scared to do anything themselves.

 

[Greg72]

Best of luck to you...

From the sounds of your previous posts and the questions you've asked it doesn't sound like you had a good understanding about how to get the stock 350 running right... and you've been struggling with it for a couple of years now.

I know you enjoy bragging that a V6 Toyota is a superior tow rig, but it actually serves to demonstrate how screwed up your engine / tire size / axle gearing combination is.

 

[nsxxtreme]

Best of luck to you...

From the sounds of your previous posts and the questions you've asked it doesn't sound like you had a good understanding about how to get the stock 350 running right... and you've been struggling with it for a couple of years now.

I know you enjoy bragging that a V6 Toyota is a superior tow rig, but it actually serves to demonstrate how screwed up your engine / tire size / axle gearing combination is.

Well thanks for the useful input. Nothing wrong with my axle gearing nor tire size. My axle combination and tire size isn't much different then what you have in your sig. The problem is the turd stock 350. I don't intend to change the tire size as I enjoy midly off roading the thing.

I started with new 4.56s gears which came with the truck when I bought it. Which has been said by many people on this forum as adequate with 35" tires. I see this gearing recomendations all the time. Those grenaded and were new when I bought the truck. Which IMO is what caused the engine to give up. I always had to shift to second in order to do 55 mph which pegged the rpms. I'd pay anyone $200 if they can tow my boat up 26 55mph with a stock 350 4.56 gears and 35" tires and not have to slam it in second. Its just not going to happen no matter how well its "properly" setup. A friends 94 blazer with essentially the same motor, 35" tires and 4.56 gears same issue. So its not just "MY" motor or "MY" setup. Which currently I have 5.13s and 35" KM2s. This year has been crappy as far as weather goes. So while I may have changed the gears a while ago the truck hasn't really been used until about a month ago. I have 5 cars and this one is used primarily to tow the boat and to bash in. I bought this truck because the entire truck is cheaper then a replacement transmission in my Range Rover and for that it has served its purpose.

Now matter how you slice it the stock blazer on 35s is a crappy tow rig. It's got 220hp and essentially a 3 speed transmission no way to sugar coat that. I'll give you that the Toyota's I've driven were not on 35's they were on 33's. So maybe that 2 inches makes a HUGE difference. But they also were not regeared. Maybe you haven't towed with a Toyota before? I'm not trying to convert anyone just venting my frustration. I bought the blazer over another Toyota because originally I wanted cheap and I think I was a little more hopeful on the American stuff then what was reallity. Also the downside of a Toyota is it's light and gets pushed around by the boat when braking even with trailer brakes. The blazer is heavy enough it doesn't get pushed around.

It's entirely possible that the distributor was bad and that is what caused the motor to go. Exhaust was so loud at the time I couldn't hear the motor new muffler got put on recently. That still doesn't make up for the lack of power as it didn't start running like crap til recently.

 

[Greg72]

How heavy is the boat/trailer combo?

 

[nsxxtreme]

How heavy is the boat/trailer combo?

Boat and trailer is probably a little over 4k lbs. If you never have any hills the truck is more then adequate with the stock motor. Once you put long steep hills like we have in Oregon in front of it, it struggled. Probably if I would have went with the 5.13s to begin with the truck would have done alright. I was able to maintane 55mph in 3rd with the 5.13 and not sky rocket the rpms by dropping into second. But everyone was telling me 4.56s were ideal. They just don't cut it with the stock motor combo and towing. Live and learn I guess.

Also the tempurature would start to climb when towing uphill, up to about 210 from 190. Probably need to get a larger radiator.

I'm hoping to get the needed torque out of the 383. But I have also thought of taking the money I would spend on the 383 and buy a newer engine and transmission combo. Something made after 97 when they dumped the 50's engine technology and were finally producing some respectable numbers.

 

[Greg72]

I have pulled a much heavier trailer (probably closer to 8500 Lbs) with a 350SBC a number of times.....

This is the setup that went from NorCal to Moab and back (2000 miles round trip) and again from NorCal to NH (3000 miles, one-way). Through the Sierra-Nevada mountains AND the Colorado Rockies.

The Suburban had a pretty basic 350SBC in it, the only changes over stock was an aluminum dual-plane intake and newer HEI dizzy. It put down something like 200HP / 292TQ at the rear wheels on the chassis dyno.

It came from the factory with the towing package, so it already had the correct axle gearing and a HD cooling system and with the exception of a few very steep climbs at altitude, this combination worked just fine.

It's a moot point now, but it seems to me that your motor was down on power if it couldn't even get the job done with a 4000Lb trailer. My guess is that with a properly running 383 it's going to be a night-and-day difference.....

It's not mystery that towing requires torque, not HP. The 383 will be a torquier motor, and as long as you are near the peak TQ of that motor at your preferred cruising speed, it should pull pretty easily.

 

[nsxxtreme]

I have pulled a much heavier trailer (probably closer to 8500 Lbs) with a 350SBC a number of times.....

It came from the factory with the towing package, so it already had the correct axle gearing and a HD cooling system and with the exception of a few very steep climbs at altitude, this combination worked just fine.

There in probably lies the difference. I have the stock cooling which it never over heated but the temps did rise while going uphill. And the places I go on a regular basis have steep climbs. Both on the way to and the way back. Around town and minimal inclines the motor I had did really good no complaints there, just going uphill I thought sucked. You also have much smaller wheels on that tow rig. I towed regularly from Oregon to Eastern Washington. Those trips were fine its mostly flat and the truck didn't struggle at all.

Like I mentioned if I would have had the 5.13s to begin with I probably would have been ok. Although I still probably wouldn't have been happy which is why I decided to do the 383. Braking stopping with the blazer is excellent while pulling a load. But I like to be able to accelerate while going uphill if I want to an not just maintain the current speed.

I wish I would have done the 383 to begin with. My only current dilema is the TBI and the transmission. A 383 with around .50 lift puts out around 412hp according to carcraft http://www.carcraft.com/techarticles/ccrp_0808_383_stroker_small_block_chevy/viewall.html

I was intending to get a BB TBI bored out to 52mm and larger injectors. Then a chip burned for this config. But I'm probably approaching the limits of the TBI. I'm also a little worried the 700R4 wont handle the added power. I did have that rebuilt and supposedly with better parts. But by my luck wouldn't be surprised if it ended up dead.