Smell Antifreeze 98 Suburban

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doofan1

Member
My tow vehicle 98 Sub with a 350 Vortec smells like antifreeze and runs like S.... Last week it started missing, then I started to smell antifreeze. Now when it's idleing and I take off the oil filler cap the engine almost dies. The oil on the dipstick looks good not creamy like antifreeze in it.

Does this sound like intake gaskets? It's got 157,000 on it and before this it started to suck oil pretty bad. it went form not using any to using a qt every 500 miles or so. I replaced the valve seals but that did not help much.

Thanks
 
bouncer

bouncer

Member
Pressure test the system. Probably the intake gasket. These engines have been known to eat intake gaskets because of the aluminum intake and steel heads. When the battles of the 2 metals is over the gasket ends up the looser.
 
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let_it_snow

New member
Intake gasket

Just did mine about a month ago. 97 tahoe. Same engine. Same problem. Very comon on these vehicles. I was using a little over a quart every 1000 miles. Took it apart and yep, the intake gaskets failed. No more oil usage and it runs much better.
 
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doofan1

Member
Antifreeze

I put intake gaskets it in once at about 100K. I suppose it could be ready for another set though.

I think the Dexcool has something to do with it.
 
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ohning1971

New member
Pressure test it first--head gaskets not nearly as common as intake gaskets on these motors!!!!!!!!

Make sure to use the updated GM gaskets, follow the instructions on torque, I usually
convert the low ft/lbs of torque to inch/lbs because my ft/lbs torque wrench won't go that low, clean bolts with wire wheel then carb or brake cleaner, chase intake bolts holes with tap and blow out, use blue(med strength) loctite on intake bolts when reassembling, go over all bolts at least 3 times with your torque wrench as intake will settle as you torque the bolts. And yes by all means flush your cooling system and get the "DEXPUKE" out!!!! Go with Green antifreeze. I would suggest doing the water pump at this time also, I've done a hundred or more of these intake gaskets jobs on these engines and If it still has the oem water pump it will fail shortly. Also replace T-stat and Quick connect coolant line on pass side of intake. Mark the distributor housing to the intake and the distributor rotor to the distributor base in two spots each assuring the distributor goes back in the right spot. This timing cannot be set with a timing light you must have a scanner to set the dist. correctly if you do not mark it well
 
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deerhunter

New member
cant pressure test for a intake leak. they only leak under pressure whern they warm up. it wont leak on idle but it will driving down the rode at 55 mph. very common for the vortec motor.
 
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ohning1971

New member
If it won't leak with a pressure test then its not leaking my friend-been doing this a long time. Most the time you can see it leak right at the front and rear corners of the intake down the block. Some times leaking internally at same time. If you warm engine up pressure test to 16 to 18 psi and leave for 15 to 20 min you will see a pressure drop if it has a leak. If it leaks going down the road it will leak in the shop--done a bunch of them for a living.
 
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miaferominka

New member
IT probally is a internal leak. That problem blew a motor in one of my work vans. Oil and Antifreeze equals a very good cutting agent.

never showed any leaking on the outside or where it was parked
 
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anonomoose

New member
ohning1971 said:
Pressure test it first--head gaskets not nearly as common as intake gaskets on these motors!!!!!!!!

Make sure to use the updated GM gaskets, follow the instructions on torque, I usually
convert the low ft/lbs of torque to inch/lbs because my ft/lbs torque wrench won't go that low, clean bolts with wire wheel then carb or brake cleaner, chase intake bolts holes with tap and blow out, use blue(med strength) loctite on intake bolts when reassembling, go over all bolts at least 3 times with your torque wrench as intake will settle as you torque the bolts. And yes by all means flush your cooling system and get the "DEXPUKE" out!!!! Go with Green antifreeze. I would suggest doing the water pump at this time also, I've done a hundred or more of these intake gaskets jobs on these engines and If it still has the oem water pump it will fail shortly. Also replace T-stat and Quick connect coolant line on pass side of intake. Mark the distributor housing to the intake and the distributor rotor to the distributor base in two spots each assuring the distributor goes back in the right spot. This timing cannot be set with a timing light you must have a scanner to set the dist. correctly if you do not mark it well
Click to expand...

So this means that my ALL aluminum block GM should have the DExcool dumped and replaced like....yesterday???
 
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ohning1971

New member
I wouldn't run that crap (DEXCOOL) in anything, but thats my opinion--I don't think GM, Ford or Chrysler ever had so many leak or corrosion problems since they started using it. They claim its extended life but I don't see how. When it turns acidic it eats aluminum worse than any green antifreeze I've ever seen. If your under warranty I'd change it at no less than every two years but use acid test strips to keep an eye on it in between.
 
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deerhunter

New member
ohning1971 said:
If it won't leak with a pressure test then its not leaking my friend-been doing this a long time. Most the time you can see it leak right at the front and rear corners of the intake down the block. Some times leaking internally at same time. If you warm engine up pressure test to 16 to 18 psi and leave for 15 to 20 min you will see a pressure drop if it has a leak. If it leaks going down the road it will leak in the shop--done a bunch of them for a living.
Click to expand...

not saying your wrong or anything
 
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skeeter2010

Member
When you remove the oiler filler cap see if you have any vacuum when you put your hand over the opening. If you do I would guess an intake gasket.
 
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