kharless

My 300 which has about 180,000 on it has a boost of about 18psi. My advice is I would leave it alone. No sense in burning anything up in a newly rebuilt engine, especially if they won't warranty it if it's been turned up. Just my opinion.

Greg

Thanks guys for the advice. I think that I will leave everything alone and be happy with it. At first I thought that I had a boost leak around a hose. Someone told me that if I hear a whistle it is'nt the turbo but a leak in the air system. I have always used cummins and am new to Mack, so I am not sure.

Hi I am a long time truck mechanic and I have found out that if you ask enough people that same thing you will hear what you think is real or what you want to hear.There are alot of factors in this question and you will have to find out what model engine what turbo and is it still set to specs and then some one out here can look it up in a mack tune up book and tell you.So many people have set the fuel up on their pumps and you know that any one that has overhauled your engine is not going to set the fuel up and put warranty on it at the same time. And I know that there is truck drivers out ther that will not agree with me. my 2 cents worth

Glenn Akers

I forgot to tell you that I have a 315 hp with a air /air cooler on the front that will build 30psi but it would not dothat all day under a load without a burnt piston but I have set the fuel up on it. Glenn Akers

Thanks for the replies Glen. So, should I just leave it alone until after the warranty? I guess my question really is what can my motor take and still give me 5 years or more? Here in West Virginia a person can get some conflicting advice from old coal haulers as compared to the dealer.

I recently had my motor rebuilt by my local Mack dealer. My boost gauge shows 17 psi maximum. Allentown Mack said this is good as well as my local Mack dealer. However, a good friend of mine who has been running Macks successfully for 30+ years has told me that I should boost 23 psi minimum. Who is correct here? My turbo is new.

I replaced the 6 speed in my 1988 R686ST with a Eaton 9 speed direct. I really did'nt gain any highway speed. I should have used the overdrive(14609b instejava script:emoticon('', 'smid_10')ad of 14609a).