Bill Ran Posted October 15, 2018 Share Posted October 15, 2018 We have 2 problems with this truck, 1. small amount of antifreeze coming out of blowby tube while running. It goes through 1 gal every other week. 2. There is a rattling sound when compressor comes on and goes away when the governor cuts out. Compressor , governor and air dryer has been replaced. Truck is an 04 RD 688s with a 427 and 18 spd trans vin 067670, any help would be appreciated. Quote Link to comment https://www.bigmacktrucks.com/topic/54564-anti-freeze-coming-out-of-blowby-tube/ Share on other sites More sharing options...
fjh Posted October 15, 2018 Share Posted October 15, 2018 (edited) I personally would be more concerned about the anifreeze situation You need to pull the pan and put a pressure test on the cooling system to identify wear the coolant has come from! Oil cooler? or Liners are the common areas There are some other areas of interest Not as likly but not worth mentioning till you check The first step Specially if this has just started! Edited October 15, 2018 by fjh Quote Link to comment https://www.bigmacktrucks.com/topic/54564-anti-freeze-coming-out-of-blowby-tube/#findComment-407943 Share on other sites More sharing options...
Bill Ran Posted October 15, 2018 Author Share Posted October 15, 2018 We are planing on pulling the pan and do pressure test. I can not remember that while doing the pressure test what the problem is in relation to where the antifreeze is coming from like outside the liners or inside, if this makes sense. What I can't understand is why does it come out of blowby. Pulling pan this weekend. Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/54564-anti-freeze-coming-out-of-blowby-tube/#findComment-407944 Share on other sites More sharing options...
fjh Posted October 15, 2018 Share Posted October 15, 2018 (edited) Vaporized By engine heat! Your valve covers will likely be full of goo depending on how long this has been going on! Heat rises nature of the beast! It will likely be coming from around the outside of the liner silicone is used to seal the lower liner lip ! We've had very few oil cooler issues! head plugs can leak as well however very remote! Edited October 15, 2018 by fjh 1 Quote Link to comment https://www.bigmacktrucks.com/topic/54564-anti-freeze-coming-out-of-blowby-tube/#findComment-407952 Share on other sites More sharing options...
br549 Posted October 15, 2018 Share Posted October 15, 2018 Pull vavle covers and check the big pipe plugs on top of the heads. You can see signs of crusted antifreeze around them if they are leaking. If they are pull and put pipe thread sealer around or rubber silicone and re install. I would also check oil cooler too. We have seen it leak around the big o ring on the end, we had one that would not show under pressure, put it back on and pulled the oil pan and showed no leaks, finally we replaced the oil cooler and it cured it. Happy hunting. Quote Link to comment https://www.bigmacktrucks.com/topic/54564-anti-freeze-coming-out-of-blowby-tube/#findComment-407959 Share on other sites More sharing options...
wilbur Posted October 15, 2018 Share Posted October 15, 2018 Wouldnt the oil cooler leak oil into antifreeze.? Had this happen. There is 60psi on the oil and 10 psi on the coolant. I would think the 60 would win. Quote Link to comment https://www.bigmacktrucks.com/topic/54564-anti-freeze-coming-out-of-blowby-tube/#findComment-407964 Share on other sites More sharing options...
Mack Technician Posted October 15, 2018 Share Posted October 15, 2018 22 minutes ago, wilbur said: Wouldnt the oil cooler leak oil into antifreeze.? Had this happen. There is 60psi on the oil and 10 psi on the coolant. I would think the 60 would win. Till you shut the engine off, then there is 0 psi oil pressure and 15 PSI coolant. Generally you will see oil in tank first, but always change oil immediately after a cooler failure. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/54564-anti-freeze-coming-out-of-blowby-tube/#findComment-407966 Share on other sites More sharing options...
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