98 Buick lesabre,p0420 code, o2 sensors?cat?

[ejes]

Originally Posted By: Merkava_4


You took it the wrong way. Didn't mean to sound condescending. I'm offering my help to save someone from a YouTube hack. I'm good at this stuff and extremely particular. I made all the mistakes so you wouldn't have to. Similar to what "jeezus" did.




And you ain't (similar to) Jesus despite what you might think.

 

[ziggy]

Take it easy guys! Wow..my coolant was green colored,looked hours ago. The radiator,cap off,was a tad low like a cup i would say. Coolant overflow tank,level is fine. Couple i too off,with all makes,all o self coolant? ☺r should I be using recoil exclusivley? I always thought recool was orange, mine is green,what's in the lesabre

 

[ziggy]

I googled past few hours the upper,lower intake gaskets.guess it is a common problem in these gm 3800 engines. well,amazon Has Best Prices. Napa Is Marked Up A Bit,and Autozone....all Fel Pro Mind You, Not FAr BEehind. $130 autoizone,$160 Napa, And ,$98 Amazon.wow..
I don't have much experience with a pbnumativ poo c torque wrench,though I have 2 of them.never really used them. A friend,self taught mechanic,looked too tighten snug,then 1/4 a turn too tighten,then stop.it's snug.without torque wrenches.I've done the same,with good,but not precise results. Think I could do these gaskets without a torque wrench,when tightening the manifold back?

 

[ziggy]

The bolts manifold,are 11 foot lbs tightened. Don't think it would warrant a torque wrench.hardest part,is disassembling everything off the manifold

 

[Lubener]

Originally Posted By: ejes
I have a '97 LeSabre and have been through this already. Steam from the exhaust could indicate LIM gasket failure and subsequent CAT issues or failure, a common problem. Cheapest thing to start with is to check for coolant loss into the oil / oil in the coolant. If evidence of both or either, replace OEM LIM gaskets with aluminum gaskets such as FEL-PRO MS98014T, or equivalent,. While you're doing this, do yourself a favor and buy the aluminum GATES 9105119 heater hose elbow connector, or equivalent, and replace it, as the plastic OEM connector will probably break when you remove it anyway. Then replace the downstream O2 sensor with DENSO 2344087, or equivalent (I replaced the upstream too, anyway, for good measure). The CAT may still be toast, but at least you won't ruin another one if you want to keep the car.

Bottom line, you probably will find it is the LIM gasket and you have to fix it or you'll keep going through O2 sensors and CATs at the very least if the engine doesn't fail first. Fix it, and that 3800 engine will last another 200-400K miles all things being equal.

Huge amount of info here if you have the time: GM 3800

Good advice. Change out the upper manifold assy. too. It was poorly designed from the begining. Go with a good aftermarket unit which has the steel sleeve in the EGR passage to prevent the burn thru which the OEM's often did.If you find coolant sitting on top of the LIM, you will know the upper was leaking too.Don't be surprised if you have to replace the lower manifold too, as I had to. Old coolant will eat away at the lower manifold.

Also, use a torque wrench.Torque the bolts in steps working up to specs. Get one from Harbor Freight. It is better than nothing. Heard too many people cracking their plastic UIM because they over torqued it.

 

[Ihatetochangeoil]

Latecomer to this thread; lots of good advice here. I've done these UIM and LIM gaskets on several 3800 engines. The uppers were so notorious for leaks around the EGR that Dorman redesigned an aftermarket one, then redesigned their redesign. Fix the gasket issues and the engines are bullet proof. No one has ever heard of a timing chain failure on them; they're all steel; excellent oil pressure, ZZPerformance races them and says the STOCK crank and rods are good for 400+ HP. Some of these are Supercharged from the factory and aftermarket turbocharged, with STOCK bottom ends. https://zzperformance.com/3800/turbo-parts-kits/z7-turbo-kit-1.html

The UPPER manifold bolts are 89 INCH pounds in 3 steps; 22, 44 then 89; working from the center out in a sequence. You do NOT want to attempt this without an INCH POUND torque wrench. Over torque and you'll squash the plastic and ruin the piece. Under tighten and it'll leak. BTW, ZZPerformance has all the parts you need and probably some good prices too.

https://zzperformance.com/3800/air-intake/l36-upper-intake.html

https://zzperformance.com/3800/gaskets-adhesives/intake-gasket.html

https://zzperformance.com/3800/gaskets-adhesives/aluminum-coolant-elbows.html

 

[Merkava_4]

Greyworks 106001

FELPRO MS98014T

Dorman 47065HP

These are the parts I used. The first thing you do is disconnect the negative battery cable. The second thing you do is drain the radiator. The third thing you do is disconnect the wiring harness that's in the way of pulling the upper intake manifold. You're going to need a torque wrench. The LIM is 189 inch pounds and the UIM is 89 inch pounds. You're going to need blue Loctite for the bolts.

 

[ziggy]

Sorry guys! I see my tablet types rexcool,recall. It has spellcheck.should I be using dexcool? Or should I use all makes,all models coollant?

 

[Lubener]

Originally Posted By: ziggy
Sorry guys! I see my tablet types rexcool,recall. It has spellcheck.should I be using dexcool? Or should I use all makes,all models coollant?


I stuck with the Dexcool. I am not convinced it is all that bad, if maintained. I echo Merkava's parts suggestion. I used them too with great results. I went one step further and peeled the o rings from the Dorman elbows and replaced them with the Delco's, slightly thicker and heard about leaks developing with the Dorman orings after a year or so.

 

[ziggy]

Phrw! I fotrgoit,I have an ad delco digital torque cube i bought few years ago,little battery operated red cube you put on a wratchet,covers 3 -59 ft lbs! So for me, it's 7 1/2 foot lbs, and 11 foot lbs.

 

[Merkava_4]

The main thing is not to mix brands. It can cause the coolant to foam. I use Dexcool for the color.

 

[ziggy]

Yeah I figured,not too mix brands.I have no idea,what's in it,other than out a green in color,since I purchased this car 2nd hand. Well,for today, should I at least change my oil? It was already dark brown,and ran a bottle of humour high mileage fuel system cleaner, in 1/2 tank,now near empty tank. With these probs,should I change the r oil,or wait till I get the p0402 problems fixed?

 

[Merkava_4]

If you're going to be changing intake manifold gaskets fairly soon, you might want to wait until after that to change the oil. You might get coolant dropped into the oil.

 

[ziggy]

Well,I have till end of month,too go through emissions. So I called midas,get a quote on a new cat,for refference.use Ha be too order new 02 sensors,rockauto,and wait till next week too install myself.autozone,napa,want $53 each,rockauto,$27 each. Then see what happens.if the price is right,midas, I'll do them.then after that, if coolant disappears,so the gaskets. I bought the car,like 2 weeks ago.dm v said I have 30 days,emissions,but if I don't do it,have 60 days,but will not affect my registration. So Im Trying TOO balance thinfs . Not SUREe I wanna leaAbe brown GUMOut FUEo system cleaned OIL and drive Without An oil change...feel better DOING it.

 

[ziggy]

Was planning on as delco oil filter non ecore, and Castrol 0w30 or Pennzoil ultra.but have like 15 year old stash of gasoline motor oil..use too flush every year or 2.maybe I'll do that

 

[Merkava_4]

The problem with the original LIM gaskets is they were not metal backed; therefore they crack and break apart over time causing the leaks. I actually found my LIM gasket leaking externally.

The original UIM had an EGR tube that was too big and melted the plastic UIM. The new Graywerks UIM comes with a reduced diameter metal EGR tube that you replace the original with. The Graywerks UIM also has a metal bushing installed where the EGR tube goes through. Both the FELPRO LIM gasket kit and the Graywerks UIM kit is a permanent fix.

You're also going to need to get a tube of silicone grease for the coolant elbows (I recommend Dow Corning 111) and a tube of Permatex Ultra Black for the LIM installation. We'll work out all the details once you start the job.

 

[ziggy]

Thanks! I am doing an oil change,flush,since it's unknown history. Oil came out black,some off brand sounds like a prospect napa,but isnt. Opened the filter,some black funk at bottom.it was down overt a quart too,about quart and 3 quarters ermpty,the sump. Running some old chevron 5w30 I had stashed,I bought like 10 years ago,and na pad cheapest filter,my or something it's called. Idled for 30 minutes or so, letting it cool down, your and half or so..go back out,drain it,and till with Quaker state synthetic 3 quarts 5w30, 1 1/2 10w30,and. A a.c. Delco filter i bought last week,at local advance auto.gonna have too do plugs another day,as it's getting dark now,and rain is coming,here in southwest ct.

 

[ziggy]

I did noite,when car was idleing,during flush,what appeared to be light condensation kept coming out,but eventually went away,after like 15 minutes. I smelled it,kinda had a sweet smell,so I'm assuming it's coolant,.I'll check coolant level too.I added just a tad,of supertec h all makes and modeks,I had since last year.it was down only like 4_6 ozs.

 

[mk378]

Keep an eye on coolant level. When you take the spark plugs out, if you see one of them is a lot cleaner than the others, there's a leak into that cylinder.

 

[ziggy]

Yup! Thanks for reminder! A 2nd hand car,as as someone else's neglected problems,now mine. Plus,they don't make cars like they used too! A friend some 22 years ago,bought a 1957? Plymouth valiant, all original radio,chrome it was so beutiful.some priest owned it,had only 38,000 miles on it.priest never have it an oil change. Friend went to do an oil change, New oil,filter,he said it sprung leaks from all over the engine,kinda like a waterfall.the sludge is what was holding it together,he had too junk it. Only paid $400 for it.