LIM Gasket change

Hi!

First some data:
Blazer 1995 ODB2 4.3L V6 VIN W CPI Vortec

I'm in the process of replacing my Lower Intake Manifold Gaskets. When I cleaned the the LIM I found some "pitting" at the coolant ports.

How do I best deal with it?
Put some RTV on it?
Do nothing?

It is not much but I like to be sure it does not start leaking coolant again...

/Fred

Attaching a pic:

Freddy,
If the pitting in the picture is the worst of it, don't do anything. RTV, silicone, etc, is NOT recommended. Make sure you use this gasket set: http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Intake-Manifold-Gasket-Set-Felpro_19783624-P_102_R%7CGRPGASKAMS_842129288___

Clean the threads on the bolts and in the heads with a tap and die set. Then put sealer on the bolts when installing them. Very important to use proper torque specs and tightening sequence. Make sure all gasket surfaces are clean, use acetone if necessary. Follow the instructions that come with the gasket set. If these gaskets are installed correctly, they will not leak.

Freddy,
If the pitting in the picture is the worst of it, don't do anything. RTV, silicone, etc, is NOT recommended. Make sure you use this gasket set: http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Intake-Manifold-Gasket-Set-Felpro_19783624-P_102_R%7CGRPGASKAMS_842129288___


Thanks for the quick reply.
I have another Fel-Pro gasket set with blocked rear coolant ports. As the Intake Manifold only have coolant ports in the front, it looks fine.

The Intake Manifold at the rear (nonexisting) ports have more pitting, but I don't think that is a problem due to the blocked gasket ports. Attaching pics of them too.



Clean the threads on the bolts and in the heads with a tap and die set. Then put sealer on the bolts when installing them. Very important to use proper torque specs and tightening sequence. Make sure all gasket surfaces are clean, use acetone if necessary. Follow the instructions that come with the gasket set. If these gaskets are installed correctly, they will not leak.

Have cleaned everything with acetone. Have not read anywhere else to put sealant on bolts but I will do that.

/F

The threaded holes in the cylinder heads are not blind holes, they go all the way through. That's why they need to be sealed. The sealant also helps to keep the bolts from vibrating loose. Use Loctite 2423 thread sealant. It will seal the threads when it cures but the bolts can still be removed with hand tools when necessary.

The pitting in the second pictures looks like it isn't in the area of the gasket but is where the gasket isn't. That's were they used to have coolant bypass ports through the manifold and now they don't. I would go with the advise you've been told, no sealant on the gaskets, no worries.

The pitting in the second pictures looks like it isn't in the area of the gasket but is where the gasket isn't. That's were they used to have coolant bypass ports through the manifold and now they don't. I would go with the advise you've been told, no sealant on the gaskets, no worries.


I have now done as you both advise and reinstalled the LIM without sealant on the gasket.
Tomorrow I will install the rest and see if it works...

Freddy, we'll be waiting ;)

An update:
On Thursday night I put the rest back (new t-stat, dist cap and rotor) and finished all but refilling coolant.
On Friday I went out and filled it up with coolant and tried to start it up...
No start, just cranking.
Rechecked the ignition wires and noticed I swapped 1 & 3.. Then at first crank it sounded like it would start but then it died.
Hm... Start gas... Same again... probably a fuel problem.
Did I remove the plugs in the fuel line connections in CPI unit? (I put them in to avoid getting dirt in CPI)

No, they were still in. Removed fuel lines and plugs (used foam ear plugs, and they really worked, not even fuel passed them :wink:)
When I got it all back in place again, it started at first crank! :D

The new T'stat is an ACDelco, and now my temp is back to normal. I thought it ran a little cold before and twice replaced T'stat (no ACDelco) without improvement. So it pays to get the right brand parts!

So far I have not noticed any coolant leaks, so it looks good.

Thanks for your help.

/Freddy

Glad you got her fixed, and thanks for posting back!

OK, I'm back.
:banghead:
Now is the water pump leaking trough the weep hole underneath.
I am not sure that it did not leak before I did the LIM Gasket job... but I'm sure it leaks more now.

Can you tell me if it might be caused by having the coolant system drained during the gasket change? It took a week 'till I refilled it.

Didn't think of it then but now I recall reading that, if removed, the water pumped should be kept immersed in a bucket... (read it in my old Haynes for Volvo 240)

Well, next I will have to change WP. It looks like a simple job, maybe 1.5-2h?

/Freddy

Never heard that about water pumps, can't see that it would make a difference. The main thing is to use the correct coolant. 95 was a transition year; your engine could use either the green ethelene glycol or Dexcool, don't mix the two. Should be a sticker under the hood if it requires Dexcool, or check the owners manual. There is a thread for replacing the water pump in the Blazer "How-To" section.

OK, I put in a new water pump yesterday and now it is fine, holds it coolant.

When I bought the car 5 years ago I flushed out all Dexcool and replaced it with normal mono-ethylene glycol after reading about the dexcool problems.

Replacing the WP was simple :biggrin:

Now I am prepared for the winter!

/Freddy

Freddy,

Changing coolant from Dexcool to ethylene glycol, or vice versa, is NOT recommended, unless of course, you want ongoing problems, and you'll have them, guaranteed. This link explains why:

http://www.ricksfreeautorepairadvice.com/repair-topics/cooling-system-service/water-pump-analysis%E2%80%94what-happens-when-you-use-the-wrong-coolant

Freddy,

Changing coolant from Dexcool to ethylene glycol, or vice versa, is NOT recommended, unless of course, you want ongoing problems, and you'll have them, guaranteed. This link explains why:

http://www.ricksfreeautorepairadvice.com/repair-topics/cooling-system-service/water-pump-analysis%E2%80%94what-happens-when-you-use-the-wrong-coolant

So the I problems had with LIM gasket and water pump seal is because of my change of coolant type? Then I should go back to dex-cool?
What about the Dex-cool clogging up the system, is it no longer a problem, have they improved the Dex-cool formula?

I replaced the coolant after reading at this forum that Dex-cool might clog up the coolant system. But that was about five years ago...

The glycol I used this time is "Valvoline MaxLife Coolant AF Concentrate" and dest. water (50/50)

//F

The problems you've had after changing to ethylene glycol could very well have been caused by using the wrong coolant. Dexcool is not the problem, it never has been. The problem is that Dexcool is not serviced as often as it should be, or it is serviced improperly. The factory recommended service interval was 5 years or 100,000 miles, that's neglect! A 50/50 mixture of Dexcool and distilled water, serviced, (flushed) every 36,000 miles or 3 years, will not "sludge up" or turn to mud. The system also needs to be checked for electrolysis on a regular basis. The problem with LIM gasket leaks is the fault of the design of the gasket, not Dexcool.

The same thing applies for just about everything on a vehicle, if you neglect or abuse it, you're going to have problems. For example, a lot of manufacturers are recommending 7,500 or even 10,000 mile intervals for oil and filter changes. If you ask any honest engine technician, they will agree, it is neglect and abuse. You will have problems that you would not otherwise have, IF you changed the oil and filter somewhere between 3,000 and no more than 5,000 miles.

An old race car engine builder always when breaking down an engine he would take the water pump and submerge it in a bucket of half water, half antifreeze as soon as he pulled it off.

Said when he did this he never had the problem of the water pump leaking after the engine being torn down for a few days, said he learned this the hard way.