GM CV owners

[mjmsprt40]

OK, maybe someone here can give me a pointer on this: I had a check-engine light on, the code indicated the Mass Airflow sensor so I replaced that. Check engine light is off. Now for the weird part:

If the CEL is on, the engine seems to run smoothly at all speeds. With the CEL off, which it's supposed to be, you can feel a bit of engine "judder" at any speed over 60. Feels like it might be an intermittent miss, but can't quite be sure. It's a 98, with the 5.7 engine.

 

[scottm4211]

Mine started that...suspected small head gasket leak...i put a bottle of that good head gasket sealer in...no more vanishing coolant..

Sent from my Etch-A-Sketch

Yup. Did the trick for mine too.

 

[BobWolf]

I own a 99 with a 5.7, I had a check engine light that would not go away. Its best to do this at home but if you are having issues and with a 98 Look behind the drivers side headlight you should find the ECM look at the connectors but, dont disconnect the harnesses. If you see corrosion you may be looking at a new ECM. If it looks OK pull the ECM CAREFULLY disconnect the ECM and check the pins and harnesses for corrosion. Remove the small acess cover the point the poenings down and shake it a few times. If you see dust, or hear rattling thats bad, even if its clean and quiet you may need a new ECM just due to age. It might not be giving you problems now but it will bite you in the asz soon. BTW everything goes through the E.C.M. If it all checks out reinstall the cover, a quick blast on the coverplate with some spray paint to help keep out the mosture. Spray the connectors with heavy duty silicone and CAREFULLY plug in the connectors.

I capped, bold, and underlined carefuly for a reason if you tend to be heavy handed you will apreciate the heads up as the pins are verry easy to dammage.
Good news is, Carquest has them for abbout $ 150.00 any GM dealership can reflash them. They will need the van and the new ECM. Dont install it untill the dealership is ready to reflash the van will not run at all due to the security in the computer. No, you dont have to buy the ECM at the dealership and it will probly cost you an hours labor to flash it.

Bob Wolf.

 

[mjmsprt40]

I replaced the MAF sensor Saturday, the CEL has been off since then. Saturday afternoon after the repair I did a test run, some twenty miles or so on Interstates 355 and 88 near my home. No CEL, but the engine did seem to have an intermittent miss above 60 mph.

Yesterday, I filled up with fuel (it was down to 1/4 tank) then visited my brother who lives on the Far North side of Chicago. It's not even possible to get above 40 on the Kennedy, but on 294 I did manage to get it up to speed, not sure but it seems like the intermittent missing may be less.

Today I'm scheduled for a 200 mile run, speeds along the route are at 70 mph legal so I can get a handle on what's real or not.

This latest bout of trouble seems to have gotten its start shortly after filling up at a Loves truck stop in Eastern Michigan a few days back, if so fresh gasoline from other stations may help reduce it.

A note on the ECM: For some reason known only to GM, they put that unit on the left wheel well under the brake master cylinder/hydraulic booster. It looks like the Exxon Valdez paid it a visit, alway has since I got this beast. I'm sure all that mess can't be doing it any good.

 

[BobWolf]

Nope, I have been told GM abbandoned that location because of ECM failuers. Im actualy thinking on relacating the location of mine if the harness will let me.

 

[wvcourier]

I think I may need a new Radiator, and the Water Pump has a slow leak. Should I replace the cooling fan too? The engine hasnt overheated, but I noticed the thermostat going a few notches above par on the last two hundred miles of this 3500 mile week.

 

[fastman_1]

If it ain't broke why fix it?? I've replace the water pump and at the same time replaced the fan clutch just for some peace of mind. But fans don't go bad

 

[Opel2010]

I have about 100,000 miles on my 2006 Chevrolet Express CV. I wanted to change spark plugs, but my trusted mechanic says not to bother. He claims the platinum plugs run way farther then that. How often do you other guys change plugs and do they look bad when you take them out? Also have you seen any better milage when the plugs are brand new? After your answers, I may just change them myself this weekend. I am not experiencing any misfires or roughness of any kind. I have the 4.8 engine. Thanks guys!

I had a Savana 3500 and first time when I did a tune up was around 400k miles. Next one around 700k miles.

 

[purgoose10]

I think I may need a new Radiator, and the Water Pump has a slow leak. Should I replace the cooling fan too? The engine hasnt overheated, but I noticed the thermostat going a few notches above par on the last two hundred miles of this 3500 mile week.

I've had several GM C/Vans. I would R&R the radiator. Don't mess with fixing it, it isn't worth it. Later model radiators usually leak at the top tank where it's plastic. Since you have the radiator out check the fan pulley to make sure it's tight. My last van I installed an electric fan and it came to life. Ran smoother, better mileage etc, etc. If you do that make sure you install the right fan shroud for a van. Differant than a P/up. My 08 P/UP has an electric fan, best thing GM did on that model. Radiators require service like anything else. Always clean out the fins of a radiator from the engine side forward. Don't use a lot of pressure. Why from the engine side? Pushing bugs and debree back out the front is easier and requires less pressure.
I would change the thermostate also. Don't wait till it goes, it will fail at the worst times. Flush the engine while your at it. Fan usually doesn't go bad but the bearing on the water pump may be worn. If I was doing the radiator I would change the water pump, thermo, radiator, belts and anything else up front.

 

[21cExp]

Mine started that...suspected small head gasket leak...i put a bottle of that good head gasket sealer in...no more vanishing coolant..

Yup. Did the trick for mine too.

Which "good gasket sealer" do y'all mean? Be a good thing to add to my tool kit.

 

[guido4475]

I've had several GM C/Vans. I would R&R the radiator. Don't mess with fixing it, it isn't worth it. Later model radiators usually leak at the top tank where it's plastic. Since you have the radiator out check the fan pulley to make sure it's tight. My last van I installed an electric fan and it came to life. Ran smoother, better mileage etc, etc. If you do that make sure you install the right fan shroud for a van. Differant than a P/up. My 08 P/UP has an electric fan, best thing GM did on that model. Radiators require service like anything else. Always clean out the fins of a radiator from the engine side forward. Don't use a lot of pressure. Why from the engine side? Pushing bugs and debree back out the front is easier and requires less pressure.
I would change the thermostate also. Don't wait till it goes, it will fail at the worst times. Flush the engine while your at it. Fan usually doesn't go bad but the bearing on the water pump may be worn. If I was doing the radiator I would change the water pump, thermo, radiator, belts and anything else up front.

Once a year on any of my vehicles I remove the radiator and thoughly clean it with a/c coil condenser cleaner found at home depot. I saturate it completely and let it sit and then spray it down with a garden hose. You will be surprised at the amount of dirt that comes off of it. I do the same to the a/c condenser, and all of the coolers, then I degrease the engine, and flush the cooling system on the engine after removing all of the hoses, and replace all of them as well, every hose. Better to be safe than sorry.I also check all of the pulleys and tensioners, along with all of the belt driven accessories. You will be amazed at how much better youre a/c will work, much colder, especially at an idle, which by the way, if you have warm a/c at an idle, save the money and do this first.The air flow cant make it to the condenser if all the fins are plugged up with dirt and fuzz. Most of the time the dirt and fuzz will collect between the condenser and the rad, where you cant see it, unless you pull it out. Take a Saturday and take youre time doing this, you'll be glad you did.

 

[BobWolf]

Add the cooling systeme sealer after each flush and fill it will seal the cooling systeme and find the pores long before they leak. Stay away from the products with solids like the old school Bars that had the pelletes. Peak Prestone and BG are decent products. If you do sspring a leak pour a can of black pepper in the radiator it will usualy seal the hole long enough to get to a shop or home if nearby and it is easy to flush out.

As for the radiator call arround to the radiator shops and see if they can score or build you a copper/brass unit. Yes you will pay for the radiator but it is worth the extra dough if you plan to keep the van a few more years. Aluminum and plastic are garbage. Fans usualy dont go bad unless they impact somthing that fell into them, a collision with somthing that penetrates the grille, or the fan cluch goes and the fan walks through the radiator. Do replace the fan cluch if you have years and miles on it.

Good luck
Bob Wolf.

 

[guido4475]

Add the cooling systeme sealer after each flush and fill it will seal the cooling systeme and find the pores long before they leak. Stay away from the products with solids like the old school Bars that had the pelletes. Peak Prestone and BG are decent products. If you do sspring a leak pour a can of black pepper in the radiator it will usualy seal the hole long enough to get to a shop or home if nearby and it is easy to flush out.

As for the radiator call arround to the radiator shops and see if they can score or build you a copper/brass unit. Yes you will pay for the radiator but it is worth the extra dough if you plan to keep the van a few more years. Aluminum and plastic are garbage. Fans usualy dont go bad unless they impact somthing that fell into them, a collision with somthing that penetrates the grille, or the fan cluch goes and the fan walks through the radiator. Do replace the fan cluch if you have years and miles on it.

Good luck
Bob Wolf.

Another driver and I were doing a 2 truck load about ten years ago together. He sprung a leak, a pretty good one, at the radiator. He asked me to go down the road and get some water and a dozen eggs..lol....I came back, and he was cracking them eggs, pouring them into the radiator, one by one.....he started it up, and filled it up with water and away we went....oh yea, it worked alright, but he also ended up replacing everything in the cooling system....lol..

 

[BobWolf]

Ive seen the egg trick but youre right you replace more than a radiator. Nice thing abbout black pepper is it will flush out. Any that may be left behind wont dammage anything.

Bob Wolf.

 

[BobWolf]

Another driver and I were doing a 2 truck load about ten years ago together. He sprung a leak, a pretty good one, at the radiator. He asked me to go down the road and get some water and a dozen eggs..lol....I came back, and he was cracking them eggs, pouring them into the radiator, one by one.....he started it up, and filled it up with water and away we went....oh yea, it worked alright, but he also ended up replacing everything in the cooling system....lol..

So, did you at least get breakfast?

Bob Wolf

 

[tknight]

Bars lead with carbon fiber technology for head gasket leaks works great but you might blow another gasket when you see what a bottle costs! It is cheaper than a head gasket job on a Mercedes motor!