Last post on Aug 08, 2013 at 4:15 PM
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Chevrolet Blazer, SUV
#153 of 174 Re: 91 4.3l intermittent, suddenly dies at any speed [rfletcher]
Jul 04, 2010 (12:04 pm)
I think I may have covered this one before. Anyway, you should always use a conductive lube or paste on the ICM head sink in the distributor. Do not use dielectric grease or silicone greease such as SIL Glide. Dielectrice lube is a insulator. Always replace the two ICM moumnting screws also. They ground the ICM and can corrode due to moisture and electrolysis. Unfortunately, the monting screws are a dealer item, part no. 10469668. The heat sink paste is Arctic Silver 5. and can be purchased as any computer electronics store.
The ICM is sensitive to heat and ground and will intermittenly fail when the heat is excessive there high resistance to ground. .
#154 of 174 Re: 91 4.3l intermittent, suddenly dies at any speed [rfletcher]
Jul 04, 2010 (7:01 pm)
Try applying a heat gun to the crankshaft position sensor. These will only set a code if the failure occurs three times without cycling the ignition. If weak, they tend to fail when hot, and at higher rpm. The unit is what's called a Hall Effect sensor. Reads the magnetic pulse from the crankshaft and will kill the engine if it doesn't "see" the pulse.
#155 of 174 Re: 91 4.3l intermittent, suddenly dies at any speed [duntov]
Jul 05, 2010 (3:53 am)
Thanks, I will certainly do as you suggest. I think a paste came with the new ICM but have no idea what it was. I had a gut feeling that it was heat related but not in this way.
#156 of 174 Re: 91 4.3l intermittent, suddenly dies at any speed [jlflemmons]
Jul 05, 2010 (4:01 am)
Thanks for the help. I will check that too. Has never set a code but then the OBD1 dosn't read a lot. Seems the guys in the shop here lack your experience.
#157 of 174 Re: 91 4.3l intermittent, suddenly dies at any speed [duntov]
Jul 06, 2010 (1:13 pm)
As you suggested, I pulled the ICM, cleaned all surfaces, and reinstalled it with the only silver product I could find. Holiday weekend. Today, in the very fine print I noticed this product, while claimed to be 99.9% pure silver and made for high power heat sinks, is not electrically conductive. Makes no sense but now I feel that I should pull it again. Your opinion.
#158 of 174 Arctic Silver 5
Jul 06, 2010 (3:02 pm)
Arctic Silver 5 is THERMALLY CONDUCTIVE, and was designed to conduct heat, not electricity. The heat sink for the ICM is designed to conduct heat away from the module and Arctic Silver 5 enhances that conductivity.
New fasteners provide a good electrical ground for the ICM and should be replaced when the ICM is replaced.
#159 of 174 Re: Arctic Silver 5 [duntov]
Jul 06, 2010 (4:53 pm)
I understand the thermal issue but misinterpreted your post as to electrical aspect of the paste because of the potential failure of the screws.. Turns out the paste from Radio Shack is in fact Arctic Silver 5 marketed under their label so I am good to go. Will see what happens. Thanks
#160 of 174 engine problems-help!
Jul 14, 2010 (12:05 pm)
i have a 95 chevy blazer that is running like i'm trying to burn pond water. i can pour sea foam in the tank and for a few days it clears up, and then back to the problem again. it also is, apparently, having vaccum problems. when it is running poorly, if i put it under a load ,such as going up a hill, the a/c will start to blow through the defrost ports. the brakes also feels like i'm stepping on a brick. it furthermore will start to overheat during this time-any suggestions?
#161 of 174 91 S10 Blazer 4X4, 4.3 L, more intermittent engine problems
Jul 25, 2010 (1:53 pm)
Since post of 6 July have had no more stalling in traffic. Thanks duntov. Now,again intermittently, the engine will not start without WOT, but it will start, every time. Hot, cold, never know when it will occur. Following may or may not have to do with problem When it starts, vac is steady at 20 in. hot idle. WOT, momentary drop then rapid increase to 23 in. MAP test; KOEO, ref. voltage steady 5. Output term B 4.91. Hot idle output 1.45 / 1.503. Then the questionable appears. WOT [ vac as above] output drops to .923 then rises back to near idle values. Chilton book calls for rise to near 4.5. Have no idea how to interpret this. Also suspected EGR so did following; Can not see movement on this one so temp. connected vac pump in place of TBI. A small vac, 2 or3 in., caused engine to stumble, more vac, engine died. Found EGR solenoid inoperative. Very high resistance in coil. Applied 12 volts directly but no action. Again, have no clue what or if this means anything to starting problem. Of course these test would not account for a valve that is intermittently stuck slightly open. Prior to this the idle had become rough. Quite a lot of vibration, especially with AC on. This is also intermittent. Shop told me it was motor mounts. These are the same guys who could find no problem concerning the previous post.
#162 of 174 84 k5 blazer ignition switch
Aug 04, 2010 (6:55 am)
Hi, does anyone know how to or can provide a diagram on how to replace the ignition module in the steering column. I looked when would not start and thought I fixed but when the column is tilted up it does not want to engage. Turn key and nothing. Lower column and it turns over. Any help would be greatly appreciated. Thanks