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1999 4.3 Intake gaskets and coolant flush #4456554
07/11/17 06:50 PM
07/11/17 06:50 PM
Joined: Nov 2009
Posts: 1,057
Warner Robins, GA
nwjones18 Offline OP
nwjones18  Offline OP
Joined: Nov 2009
Posts: 1,057
Warner Robins, GA
Just picked up a new project. 1999 S10 4.3 with only 50k miles. Intake manifold gaskets are shot and oil is leaking out the back of the intake and is in the oil (I'd guess a qt or two of water in the oil). The previous owner changed the WP right before it started leaking and was just tired of messing with it. I'm assuming the dexcool was never changed and he said the heat wasn't working great so I assume heater core is stopped up as well. I'm planning on changing the oil a few times quickly to clear out the milkshake; is that all I need to do? Also the radiator looks pretty rough through the cap but doesn't appear to be leaking should I just go ahead and replace it preventatively, or run a flush though it?


1988 F-150. 4.9 I6 247k. 10w-40 Castrol Syn-blend ACDelco UPF2.
2005 Cadillac STS N* 108k. 5w-30 Castrol Magnatec ACDelco Classic PF61
Re: 1999 4.3 Intake gaskets and coolant flush [Re: nwjones18] #4456584
07/11/17 07:22 PM
07/11/17 07:22 PM
Joined: Sep 2005
Posts: 352
Empire State
pair of Blazers Offline
pair of Blazers  Offline
Joined: Sep 2005
Posts: 352
Empire State
had the same thing w/01 Blazer plus the poppet valve problem.
If your going to open it up check to see if the "spider" was changed to the new style one.
thread from this board
https://bobistheoilguy.com/forums/ubbthreads.php/topics/1115158/Re:_01_ChevyBlazer_6100_mi_on_#Post1115158
thread on it from another board
http://s-seriesforum.com/forum/showthread.php?t=79763
good luck.


91 4dr 4wd hot rod - 01 2dr 4wd sold - 14 KIA Sportage
12 KIA Forte work - 16 Honda CRV Mom's - 14 Honda CRV G/F
Fun=Fuel
Re: 1999 4.3 Intake gaskets and coolant flush [Re: nwjones18] #4456736
07/11/17 09:01 PM
07/11/17 09:01 PM
Joined: Dec 2013
Posts: 2,087
socal
barkingspider Offline
barkingspider  Offline
Joined: Dec 2013
Posts: 2,087
socal
I had this happen on an 02 S10. After replacing the intake manifold gaskets and valve cover gaskets, I recommend replacing the radiator, heater core, all coolant hoses, coolant overflow tank, and water pump. Then change the oil, drive for a day, change oil again, then do short oci until u are satisfied all coolant is gone from the crankcase. This is what I did, truck ran normal, had good AC and heat, zero leaks


06 Cadillac Escalade Ext
17 Cadillac ATS (wife)
05 Toyota Camry (daughter)
11 GMC Canyon off-road (daily)
Re: 1999 4.3 Intake gaskets and coolant flush [Re: nwjones18] #4456743
07/11/17 09:06 PM
07/11/17 09:06 PM
Joined: Sep 2013
Posts: 10,435
Indiana
dlundblad Offline
dlundblad  Offline
Joined: Sep 2013
Posts: 10,435
Indiana
I just took the intake off my '97 today this evening. I was leaking coolant around the entire thing, but it wasn't near as bad as yours. I've had it since March and added coolant the day I brought it home and have put about 6k on it.

When you buy the gaskets, buy the upgraded Fel Pro 98002. The kit came with gaskets for the injector setup, plenum and valve covers too.

I'm personally thinking about giving the Mercedes citric acid flush a try. I found an online source for $17 shipped.


03 Jeep WJ 4.0 200k Castrol Edge 10w40 HM Fram XG16
02 Volvo S60 2.4T 177k M1 0w40 Mahle OX149D
97 Chevy Blazer 4.3 149k Rotella T5 10w30 Supertech ST3980

Re: 1999 4.3 Intake gaskets and coolant flush [Re: barkingspider] #4457391
07/12/17 03:37 PM
07/12/17 03:37 PM
Joined: Nov 2009
Posts: 1,057
Warner Robins, GA
nwjones18 Offline OP
nwjones18  Offline OP
Joined: Nov 2009
Posts: 1,057
Warner Robins, GA
Originally Posted By: barkingspider
I had this happen on an 02 S10. After replacing the intake manifold gaskets and valve cover gaskets, I recommend replacing the radiator, heater core, all coolant hoses, coolant overflow tank, and water pump. Then change the oil, drive for a day, change oil again, then do short oci until u are satisfied all coolant is gone from the crankcase. This is what I did, truck ran normal, had good AC and heat, zero leaks


I like your style, but there is no way I'm messing with that heater core if I can flush it out and it doesn't leak.. What a pain in the butt. I can get a radiator off ebay/amazon for $50 so I may just go ahead and do that.


1988 F-150. 4.9 I6 247k. 10w-40 Castrol Syn-blend ACDelco UPF2.
2005 Cadillac STS N* 108k. 5w-30 Castrol Magnatec ACDelco Classic PF61
Re: 1999 4.3 Intake gaskets and coolant flush [Re: nwjones18] #4457855
07/13/17 04:23 AM
07/13/17 04:23 AM
Joined: Jan 2011
Posts: 2,711
N.Ohio
Lubener Offline
Lubener  Offline
Joined: Jan 2011
Posts: 2,711
N.Ohio
Originally Posted By: nwjones18
Originally Posted By: barkingspider
I had this happen on an 02 S10. After replacing the intake manifold gaskets and valve cover gaskets, I recommend replacing the radiator, heater core, all coolant hoses, coolant overflow tank, and water pump. Then change the oil, drive for a day, change oil again, then do short oci until u are satisfied all coolant is gone from the crankcase. This is what I did, truck ran normal, had good AC and heat, zero leaks


I like your style, but there is no way I'm messing with that heater core if I can flush it out and it doesn't leak.. What a pain in the butt. I can get a radiator off ebay/amazon for $50 so I may just go ahead and do that.


Replacing all that is total overkill.


The "thinking" man's friend.
Re: 1999 4.3 Intake gaskets and coolant flush [Re: nwjones18] #4458252
07/13/17 01:05 PM
07/13/17 01:05 PM
Joined: Jan 2004
Posts: 4,142
California
nthach Offline
nthach  Offline
Joined: Jan 2004
Posts: 4,142
California
You can try to flush out the cooling system with a detergent to try to get rid of the oil residue and then with citric acid to put a dent on the Dex-Sludge. The Mercedes guys who do acid flushes say to begin using Shout as the detergent.

A few here say if you can find old school phosphated Cascade(I think P&G sells it as Cascade Professional fryer cleaner), even better as you have something that doesn't foam up.


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