When my Blazer sits for a prolong period of time meaning (3 hours +) and i start it up it has this wierd slit knocking sound to it. I put it in reverse and my RPM's droped to about the half way mark (500) RPM's and started to idle a little ruff. The thing in reverse happened for the first time today but i've noticed the noise when starting in it now for about 3 weeks. The noise does go away when i drive it down the street.

I will try to do a sound clip of the noise later I tried just now and the sound wasnt there cause i started the car and moved it 10 minutes prior.

Heres a clip of the time i started it the second time with the camera. You can hear the knock about 10 seconds into the clip, like i said this isnt the best quality sound clip of the noise I will try to get a better quality clip of the noise when the engine is cold.

http://venomgaming.net/noise.WAV

How is the coolant level? Check your intake gaskets, you could have a coolant leak, leaking onto the lifter(s) and usually the lifter closest to the coolant leak will make noise. I really can't make out the noise, especially when its revved but it sounds like a lifter noise.

Yea i was thinking that to, I've noticed that my blazer likes to get hot meaning In about 100 Degree Heat after driving on the freeway the temp will go up to 220 to 230.

BTW Would the Poweraide Throttle Body Spacer Void My Warrenty?

BTW Would the Poweraide Throttle Body Spacer Void My Warrenty?

It depends. The reason I say that is some warrenties stipulate no modifcation to OEM setup, others could be flexable. I would say it would probably void it.

Throttle body spacers do nothing for a 4.3L.

The start up knock you are hearing is probably from dry start up knock.

Are you using a Fram oil filter?

Also, when the engine is cold, undo the rad cap and see if it is full right up to the top, if not fill it up with dexcool and go get a new rad cap.

Do NOT install another AC Delco.

Ok well its easy to remove it anyway, I will check it tomarrow but yea it got to 240 F today it happens at idle but when i get on the freeway or drive it above 20 mph it cools off.

And no i'm not using fram.

Sounds like the cooling system is not up to par and the cap is not holding pressure.

A dead cold engine with the rad cap off with probably show that the coolant level is down in the rad. You need to top it off with dexcool, top the overflow tank off and install a new rad cap.

Plan on doing a flush and fill on your cooling system soon.

These engines do not like running hot, with it going up and down, large fluctuations, its not good on the motor. There is a cooling system problem somewhere. If it goes down as soon as you start moving, it could be various things. It could be something as simple as low coolant(which presents another problem in itself), bad rad cap(as LT mentioned, very common), sludge build-up in the rad, causing poor coolant flow, and hence poor heat transfer (poor maintenance, bad rad cap, etc. can cause this). How long has the temp been going erractic like that?

The first thing I would do here is a cooling system pressure test, make sure there are no leaks in the system. If that checks out alright, I would flush it completely and properly, throw a new rad cap on, and take it from there.

i would be vary critical in closely looking at the intake gaskets at this point.

Ok i'm doing a rad flush tomarrow and i'm getting a new cap. Its been doing it for about 2 weeks now i hardly have been driving my car right now. I'm also going to be replacing the cap tomarrow as well. I hope this fixes it i dont want to lose my baby :(


The Rad was Rust Colored (DexCool Probably) and it was cloudy and i noticed crust on the rad cap.

Ok My car is acting extremely wierd , I was sitting at a drive threw and my oil presure indecator started to spaz out a little bit and the RPM's dropped from 600 to about 550 or just above 500, I moved it into neutrul and it went back up to 600. Could this be a cooling problem still ?

my bravada makes the same noise but does not get hot. how many miles do you have on your blazer i have 90000miles http://www.automotiveforums.com/vbulletin/showthread.php?t=594654 his does it also

73k

Ok My car is acting extremely wierd , I was sitting at a drive threw and my oil presure indecator started to spaz out a little bit and the RPM's dropped from 600 to about 550 or just above 500, I moved it into neutrul and it went back up to 600. Could this be a cooling problem still ?

Could be the MAF needs cleaning and one of two things for the oil pressure indicator.

The oil pressure sender is shot or needs the electrical connection cleaned or you oil filter is screwed.

The engine rpms control the oil pressure seeing the oil pump is connected to the distributor gear.

Ok , RPM's droping is cooling system kicking in and my mech buddy said my rad is nasty and thats whats causing th issue.

For the cold knock he said to use ProLong to coat the engine so it wont make that noise so i'ma give that a shot.

Ok , RPM's droping is cooling system kicking in and my mech buddy said my rad is nasty and thats whats causing th issue.

For the cold knock he said to use ProLong to coat the engine so it wont make that noise so i'ma give that a shot.

NO! Don't start adding crap to your oil without doing research!

Pour point: -27 deg. F
Viscosity @ 100 deg. C: 37.5 SUS or 3.41 cSt
Flashpoint: 108 deg. F
TBN (D2896 method): 6.73

Iron 7
Chromium 7
Copper 2
Lead 33
Aluminum 9
Silicon 4
Tin 13
Sodium 10
Magnesium 11
Silver 1
Nickel 5
Zinc 11
Calcium 1000+

The patent also states that Prolong is:
51.5% chlorinated parrafins
31% aromatic solvent
15.5% mineral oil
1% mineral spirits
1% calcium sulfonate

Parrafin based additives will turn to acid in your crankcase and actualy HARM YOU ENGINE!!!!

Do NOT start adding crap to a good engine without doing the proper searching.

The FTC charged these guys for scamming the public.....AVOID!!!

ASPECTS OF CHLORINATED ADDITIVES TO CONSIDER

Adhere only to ferrous surfaces (steel and iron).
Easily "washed" away, therefore, must be added at each oil change and replenished when oil level is low.
Easily burned away in an engine due to very low flash points.
Tend to evaporate.
High concentrations of chlorine can create hydrochloric acid in internal combustion engines.
Used oil may create a toxic disposal problem.
Some products use powerful solvents, such as trichloroethane, for lubricity which are highly toxic and harmful to people, pets and the environment.
Negligible effect on reducing exhaust emissions.
Do not signifcantly increase fuel economy.
High paraffin content may contribute to deposit formation.
Some products may have high total acid numbers which can affect non-metallic surfaces and ultimately metal surfaces.
Toxic emissions, such as hydrochloric acid, cannot be detected by conventional exhaust gas analyzers.

A Simple No would do the trick next time BlazerLT LOL, Just kidding thanks for the info i was thinking about getting some today.

A Simple No would do the trick next time BlazerLT LOL, Just kidding thanks for the info i was thinking about getting some today.

Just helping you out.

What oil and filter do you use now?

Use Synthetic and just a regular oil filter.

What is the regular oil filter?

Also, what brand of synthetic do you use?

Pennzoil But next oil change going to Mobil, Mile Guard is the oil filter.

Pennzoil But next oil change going to Mobil, Mile Guard is the oil filter.

There is your problem, Mileguard is made by Fram.

Avoid these filters made by Fram:

Fram Extra Guard (std)
Fram Tough Guard (different media?)
Mileguard (Jiffy)
Honda (although some are alleged to be made by Filtech)
Chrysler line up except for the Cummins
Penzoil
Deffense
Canadian Tire

why dont you just take it in if u still have a warrenty like u stated earlier

Good point, but I can almost guarantee it is his filter causing the problem.