Stumped

[runsinmud]

I have an 89 S-10 Tahoe, It had 89,000 mile,s on it when I got it, It run,s great at first then it will try to shut down, I can feather the gas and it will keep going, barely, after a bit it will blow black smoke out and run good for a while then do it all over again, I've had a new fuel pump put in but it did'nt help. Anybody know what it could be? Thank's

[molehole]

Have you checked to make sure all vacuum lines are secured properly? Make sure you throttle body is clean too. Whyen was the last time it was tuned up? Good Luck

[BlazerLT]

Have you ever done a tuneup?

[runsinmud]

Originally Posted by BlazerLT

Have you ever done a tuneup?

New fuel pump, New fuel filter, fresh tune up, cleaned injecters, New I'am, Stupid I,m not.

[rlith]

Check your timing (0 degrees TDC) Since you did a tune up (plugs, cap, rotor, wires) Look into your ignition module (under the cap) and your coil. When ignition modules go bad it's usually do to lack of dialectric grease. When it heats up it starts going bad. The dialectric grease insulates it. Just something to look at. Even though you cleaned the injectors, make sure they are spraying a fine cone pattern and not dribbling. When was the last time you replaced your 02 sensor?

[Mikado14]

Originally Posted by rlith

Check your timing (0 degrees TDC) Since you did a tune up (plugs, cap, rotor, wires) Look into your ignition module (under the cap) and your coil. When ignition modules go bad it's usually do to lack of dialectric grease. When it heats up it starts going bad. The dialectric grease insulates it. Just something to look at. Even though you cleaned the injectors, make sure they are spraying a fine cone pattern and not dribbling. When was the last time you replaced your 02 sensor?

The dielectric grease that is used is called "heatsink compound" in electronics. It's main purpose is to remove heat from the component and not just insulate.

[rlith]

Originally Posted by Mikado14

The dielectric grease that is used is called "heatsink compound" in electronics. It's main purpose is to remove heat from the component and not just insulate.

As a network engineer I am quite aware of what heatsink compound is, dilectric grease is an altogether different material. Heatsink compound actually has mineral in it that can give unwanted electrical conduction, but is meant to conduct heat, whereas dilectric grease coats and protects (it's main use) but also helps insulate from heat (not draw it away or conduct it as heatsink compound does) It also has no electrical conducting properties what so ever.

[Mikado14]

Originally Posted by rlith

As a network engineer I am quite aware of what heatsink compound is, dilectric grease is an altogether different material. Heatsink compound actually has mineral in it that can give unwanted electrical conduction, but is meant to conduct heat, whereas dilectric grease coats and protects (it's main use) but also helps insulate from heat (not draw it away or conduct it as heatsink compound does) It also has no electrical conducting properties what so ever.

rlith, first of all, I am not slamming you. You mentioned in your post that it is there to insulate. It is not, it is there to heatsink the ignition module. Also, you are correct, it better not have any conduction properties or it's purpose is defeated.

You are correct that there are different types of heatsink compound, but this is due to application and that application is usually frequency related.

[BlazerLT]

Dielectric Grease and Heatsink Compound are two completely different materials with two different uses.

Never substitute one for the other.

[Mikado14]

Heatsink compound is silicone, the same as dielectric grease, whose temperature characteristics for sinking heat are enhanced with zinc oxide and it usually is white in color. Some heatsink compounds contain boron nitride ceramic particles and are excellent when dealing with frequencies above a Gig. There are several different compounds available for different applications.

The last time I changed an ignition module, just last week, a little tube with white heatsink compound was supplied with it. It was not the clear dielectric grease as you would use with connectors, however, it could be used but it's ability to sink heat would not be as great as the white compound supplied with the module.

[BlazerLT]

Dielectric grease is not used as a heat transfer compound.

[Mikado14]

Originally Posted by BlazerLT

Dielectric grease is not used as a heat transfer compound.

I am sure, if you are truly interested, that you could do a search on the web and I am sure you will find that dielectric grease is used as a heatsink material. It is not as effective as those that are formulated for that purpose.

Dielectric grease is used in electrical connections because it prevents condensation or moisture from migrating into the connector or connections.

Heatsink compounds, notice the operative word here, compound, are formulated for the transfer of heat. The base used is silicone, but there are others as I stated for specific applications.

Silicone grease or dielectric grease was used back in the fifties as a heatsink material. However, when improvements in the semiconductor field allowed higher power dissipation the need to remove heat become greater. That is when the "white stuff" appeared.

I can remember articles back in the late eighties, early nineties where dielectric grease was being used as a heatsink material on CPU's that were being overclocked whereas the compound with zinc oxide (white stuff) was causing problems.

[BlazerLT]

I know this all too well seeing I run a successful computer hardware site.

Ordinary heatsink compound is indeed silicone based but most of the high performance applications now are based on mineral oil.

[Mikado14]

Originally Posted by BlazerLT

I know this all too well seeing I run a successful computer hardware site.

Ordinary heatsink compound is indeed silicone based but most of the high performance applications now are based on mineral oil.

uh, I think this discussion could go on for I am confused with a previous post of yours and now this one. What do you say that we agree to disagree seeing as I remember what was used before you were born,(no slam intended) and that as technology is always changing with changing requirements things change or are improved.

Can you agree to this?

[BlazerLT]

All I am stating is that you don't use heatsink compound as a replacement for dielectric grease.

Can you agree to that?