I had my used engine oil tested and the results returned that I have coolant in the oil. There is a service bulletin for poor castings in the 5.3L engine. I don't know yet if this is the issue. Anyone else have this problem?
CK5
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2001 1500 Silverado - Coolant in oil, bad news from today
- Thread starter wazzabie
- Start date
88Silverado
1/2 ton status
Could be a leaky head gasket. GM puts these sealer tabs in all their new vehicles because their castings are somewhat rough. I have used them in my LS1 Firehawk when it started to loose coolant (forcing it into the overflow tank and not recovering after cool down). I also used them in a 94 Thunderbird and my old Cummins 5.9 when coolant was noted in the oil. Never had an issue after that. Worth a try. YMMV
I’ve been tempted a few times to try a version of that. But was told never to do it.
Interesting if you say it works without ill effects.
88Silverado
1/2 ton status
I first found out about these years ago from a GM mechanic at a dealership. Its in their repair manuals. They inserted them in the lower radiator hose prior to refill. He said GM uses them in all new cars. Its not aftermarket item like pep-boys stop leak. Its a GM p/n . He told me do not crush them (hazardous if you inhale the powder) just drop into the radiator and go. They have worked for me. Maybe one of the other GM mechanics on the site will chime in.
any time a 3800 cooling system was opened these tabs were required, 89ish before I left a Buick shop, for city fleet life.
Wes - were you previously a GM mechanic at dealership?
I can say this without a shadow of a doubt. In thirteen years at a Chevy dealership service department we never came across a 4.8 or 5.3 with a porous head like what is listed in the bulletin.
I’m not saying it couldn’t be possible, but I bet it’s fairly rare to find with those trucks being now 20+ years old now.
How fast is the engine loosing coolant? Did the results say it was an excessively high concentration or low concentration in the oil? Obviously there shouldn’t be any in the oil but if the concentration is in line with the coolant loss or not will provide some direction.
I would lean more to a head gasket causing the coolant in the oil but you would see the coolant contamination in the oil pretty easily.
The gm seal tabs date back to the great 4.1/4.5L v8’s used in the fwd caddies of the 80’s. They were not great at sealing head gaskets or holding its water at all. The seal tabs had the nickname of ht4100 tabs because they were developed for that engine. I don’t recall that gm was putting in seal tabs right on the assembly line.
I’m not saying it couldn’t be possible, but I bet it’s fairly rare to find with those trucks being now 20+ years old now.
How fast is the engine loosing coolant? Did the results say it was an excessively high concentration or low concentration in the oil? Obviously there shouldn’t be any in the oil but if the concentration is in line with the coolant loss or not will provide some direction.
I would lean more to a head gasket causing the coolant in the oil but you would see the coolant contamination in the oil pretty easily.
The gm seal tabs date back to the great 4.1/4.5L v8’s used in the fwd caddies of the 80’s. They were not great at sealing head gaskets or holding its water at all. The seal tabs had the nickname of ht4100 tabs because they were developed for that engine. I don’t recall that gm was putting in seal tabs right on the assembly line.
Yes from 85 to 89.5. 2 different gm agencies, the first had 5 car lines all but GMC, the 2nd was Buick only. Then I went to LAFD and were we had a 90 80s vintage G van ambulance, and some Catalina police package sedans, with the cccc computer system. Those Pontiac were cricket fast, for huge boat. 3 years later transferred to LADWP, got to work on the EV1, we had 30 of them. Lots of gmt400, P van and G vans. At any point DWP had @ 12k pieces of numbered equipment, ton of small engine unnumbered units we also maintained
