Hi all,

New guy here, and would greatly appreciate any help or advice you can give! I have a 1996 LS 4-door Blazer 6 CYL, 4.3L with only 85K miles. I'm not mechanical, but know an honest mechanic and he is not sure what is causing my problem.

To make a long story short, my Blazer seems to run ok on level ground, but when I go up a long 2-mile hill on my drive to work, towards the top I have been sporadically hearing a "whirring" or high-pitched "wheezing" noise for about 10 seconds (almost like something is deflating?) followed immediately by a fairly loud "thump" -- then the whirring stops and the vehicle runs normally. I'm concerned about this wondering if it's a safety issue or if the engine could suddenly die etc. Any ideas what this could be or how to fix this?

My mechanic checked hoses and said they were secure. The last time this happened in April, he replaced a part of a vacuum hose and pcv hose (?) and this strange noise stopped until now (about 6 months later).

FYI: I've had alot of work done on the vehicle earlier this year (by differ repair facilities), i.e., had my transmission checked out and serviced and it was ok, also had the fuel injection replaced along with upper intake gasket, oil pan gasket replaced, valve cover gasket, front main seal, intake manifold gasket, spark plugs, cap & rotor, transmission coolant lines replaced. The current problem started after most of this work was done earlier this year.

Thank you for any help, and hope my descriptions are ok...

p.s. in September, my mechanic did a smoke test and found no leaks, and replaced the vent solenoid.

 

Have you serviced the rear end?

 

Just a thought, but could it be the fan clutch? I haven't been around them much, but is it possible the fan is coming on causing the whirring, then disengaging harsh enough to make a clunk? Hopefully someone can confirm or deny my though.

 

Thanks for the responses. Not sure if much work has been done to the back, just the items outlined above. And I'll have the fan clutch checked.

It's aggravating and perplexing because these noises stopped for about 6 months after they first started, and now they're back. As I've spent alot of money on this vehicle this year, I'd like to get another year or two out of it if I can. Anyway, I'll be going up the hill today and see if it happens again and if you have any other ideas, please post.

 

Does the engine heat up during this hill climb? It could be a combination of things from the fan clutch sapping power due to the increased heat from the hill climb to a possible problem with the engine. I have seen a few catalytic converters get restrictive on long climbs before finally choking off completely.

 

Hi swartlkk,
As far as I can tell from the gauges at least, the engine does not heat up climbing the hill. It's strange, I climbed the hill earlier today and it didn't make these noises, but the other the vehicle did make these noises, so it's happening sporadically. Thank you for your input.