Gary Lewis Posted September 5, 2023 Share Posted September 5, 2023 Thanks for replying, Gary. After converting your data sheet to millimeters, my bolt comes in at about 3 mm shorter (approximately 55mm) than the shortest bolt listed there (2 19/64" converts to 58.34mm). I guess I'll know for sure what's what if I do decide to pull the heads, as I can of course then compare that bolt with the rest. The 14 in front of each measurement in that data sheet: does that denote the thread count? I feel reasonably okay about replacing the valve seals: that doesn't appear to be too technically involved a process. I'm not so confident re the valve guides, however...wouldn't that be a job for the engineering shop? I'm still looking for a conclusive answer as to why I have so many bent push rods. Malfunctioning hydraulic tappets are one possibility, I believe. How do you check a tappet...what do you look for? Thanks again, mate. If the bolt is that short then it may have been replaced. But you've had the truck for 33 years and until recently it has been reliable? That doesn't add up. As for what bent the push rods, someone on here recently had bent pushrods due to bad fuel. It gummed up the valve/guide clearance and the valves didn't want to open. But didn't you say you are running LPG? If so I wouldn't think you'd have the same problem. So about all I can imagine then is over revving. But a 302 shouldn't have problems with 5000 RPM, so maybe bad oil? The page at Documentation/Engines/General Engine Service has the 1985 factory shop manual section entitled General Gasoline Engine Service, and it has a discussion about lifters starting on Page 4. If your oil had something gummy in it the lifters could fail to compress and that could bend pushrods. So check out that section on how to clean lifters. And yes, valve guide replacement does require some special tools so I'd take the heads to an engineering shop. Link to comment Share on other sites More sharing options...
Kevin Elvey Posted September 6, 2023 Author Share Posted September 6, 2023 If the bolt is that short then it may have been replaced. But you've had the truck for 33 years and until recently it has been reliable? That doesn't add up. As for what bent the push rods, someone on here recently had bent pushrods due to bad fuel. It gummed up the valve/guide clearance and the valves didn't want to open. But didn't you say you are running LPG? If so I wouldn't think you'd have the same problem. So about all I can imagine then is over revving. But a 302 shouldn't have problems with 5000 RPM, so maybe bad oil? The page at Documentation/Engines/General Engine Service has the 1985 factory shop manual section entitled General Gasoline Engine Service, and it has a discussion about lifters starting on Page 4. If your oil had something gummy in it the lifters could fail to compress and that could bend pushrods. So check out that section on how to clean lifters. And yes, valve guide replacement does require some special tools so I'd take the heads to an engineering shop. Thanks for that, Gary. I went to your suggested resource and checked out the advice on lifters...there's a lot there to digest. I'll get back to you when I think I understand it all. Today I'll maybe bite the bullet and take off the heads...and yup, they'll be going straight to an engineering shop! Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 7, 2023 Share Posted September 7, 2023 Thanks for that, Gary. I went to your suggested resource and checked out the advice on lifters...there's a lot there to digest. I'll get back to you when I think I understand it all. Today I'll maybe bite the bullet and take off the heads...and yup, they'll be going straight to an engineering shop! Good luck! Link to comment Share on other sites More sharing options...
Recommended Posts