How does one determine a blown engine. My furure son-in-law bought a '74 VW Bus, drove it from NH to MA about 200 miles. It drove fine but seemed to lose some power. It idled a bit before he shut it down then next morning it wouldn’t start. Engine turns over but doesn’t fire up. I haven’t seen or listened to this myself but this is what he described. A mechanic, supossedly a VW expert says engine’s blown & needs rebuild or replacement. What should we look for or ask this mechanic. Being aircooled some signs I’d check don’t apply.
If the engine ran smoothly before he shut it down, it’s not ‘blown’. It may have problems, it may be worn, but a ‘blown’ engine doesn’t idle. A ‘blown’ engine typically has a hole in a piston. I worry that the mechanic would jump to that conclusion.
Get a more conclusive answer to why it fails to start… There is a book available titled “How to Keep a Volkswagon Alive Written for the Complete Idiot.” If you wish to keep the bus the book is a bargain. I feel sure there was a chapter regarding NO START. Most VW engines slowly faded away with many months of declining power. Quite a few burned a valve and would start and run roughly. If abused they would self destruct like any engine. Certainly you would need to know the compression available on all cylinders and determine if the ignition is firing and fuel is available.
A compression test would be a good place to start.
Did the 74 still use points? I had a 67 that was very fussy about points. Usually no warning, it would just stop running. I suggest a high quality set like Bosch.
Has the FSIL done the basics, like check the oil level? Did any warning lights come on? Is he at all mechanically inclined? If not, he better get a mechanic on retainer.
Unless there’s something gruesome like a con-rod through the block or terrible noises, a compression test needs to be done before the engine can be written off.
It’s kind of hard for me to imagine a situation that would be running fine one minute and then no start, but still rotating, engine the next. Air cooled VW’s love to eat valves and burn holes through the piston if they’re abused, but they usually still at least run on 3 (or less) cylinders!
Also, make sure he gets all new fuel lines througout, lots of burned-up VWs from old rubber lines breaking. And one old Mustang…don’t ask!
Compression check is Step One “lose some power” and a blown engine diagnosis could point to a serious problem.
Air-cools generally have much lower compression than other vehicles out there so 130 is fine for a vehicle like this; it means serious problems for anything else.
Where is the oil level in all of this? These things don’t have a lot of oil in them anyway.
Since many of them puke oil from a number of seams when aged it doesn’t take long for the oil to get critically low.
Loss of power could also be due to overheating caused by a broken or badly slipping charging system belt.