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2001 GMC Yukon V8 MFI 5.3T (LM7) Coolant loss/oil use/etc.

A

Actrac

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Chester, CT
My 01 GMC Yukon work truck has 195K miles, last few months I have been losing coolant daily. I was told by garage a few months ago my WPump was leaking and suspect this as my major cause. I have noticed some white foaming at oil fill cap, do these engine have a gasket issue at plenum/intake area that contributes to this cause? In last 2 months engine has starting blowing a blue oil cloud about every 6 start-up cold, and I'm using more oil now. I realize this engine is getting tired, just not sure if it worth putting money into or should I purchase long block and re-fresh it now before throwing $$ into tired engine. Do you folks have a prefered re-builder for these engines? I have noticed many websites, someone said Jasper, although they tend to stear you towards there prefered installers for pricing. This truck is daily work box, so another option is junkyard unit, are there newer engine's that will bolt in that I should consider? Not sure which code engine will be direct bolt-up. Thanks for any help with this.
 
After looking back some pages I have read the tread involving coolant loss like I'm having. I read the article explaing the cracked heads syndrome on these 01-06 5.3's. Assuming this is my problem, my engine is most likely doomed now. Question 1 is; Is there a newer 5.3 bolt-in from junkyard that will not have the bad casting heads? Do these engine re-builders install new heads that don't crack? Is it worth pulling a valve cover cover off to look for sludge, I can see some on oil filler anyway. I could most likely do a short/long block swap-out if you guys think that is best. Tranny is going good, body starting to rot alittle at rear wheel wells, frame is still pretty solid, so just need to figure if this worth moving foward, or is it a time for junkyard? I can't sell it unless someone needed it for parts I guess. My concern with junkyard engine, is ending up with a flawed head issue like I have now, Thanks again for any advise
 
If it was just losing coolant I would say water pump, but the white foamy stuff in the oil fill cap points to the cracked head problem. GM has castings that don't crack from later engines. In all honesty at 195K miles your 5.3L may still be in good shape. it isn't uncommon for the LS engines to go 250K miles and still be going strong. I know of several LS engines nearing 400K miles still going strong, and this is more or less the norm with them anymore. You can put in a later engine, but you have to pull the crankshaft out and swap the tone ring on it as GM went to a different setup in 03. I'm not really up to date on much LS stuff myself, but have messed with them enough to know they can run a LONG LONG time with some basic maintence.
 
Thanks much for the the help TFerm, I was snooping around engine today, and looking at heads on internet, I was told 6 months ago by mechanic it needed a WPump, it was in shop for other work. I suspect as you with the milky stuff under filler cap I have head problems. I did read that not all the engines had the bad head, GM say's pull VCover and look for casting symbol to verify. I'm thinking to maybe try new water pump first, same time have mechnic pull VCover and inspect for signs, and verify casting ##, then I'm thinking a new set of heads and see if it will go another 50K, I only put 10K a year on this truck, so all I want is a few more years of semi-reliable use. Do you think this prudent way to go? What would you do in my shoes? Any advise appreciated, Thanks again
 
I would pull the covers and look for leaks. Get a cooling system pressure tester and pressurize the cooling system with the covers off and look for leaks. If the heads are cracked I would put another set on it or find a used engine. I was looking on CL the other night and found a few 5.3's for $300-500, and it isn't uncommon to find them for less.
 
Update/Work completed
garage pressurized system and found WPump leaking, another minor hose leak. They are convinced my heads are good by looking at oil, etc. I asked them to pull VCover and do inspection, but they were not inclined. I figure 1 step at a time. My question is; Now that leak is fixed, if my heads are in fact cracked, will I be able to watch coolant level and notice a loss?? Unrelated question about my "blue smoke plumm every 6-7 starts" , is there a way to install new valve seals with heads on?? My mechanic say's oil is cheap and just a QT when needed. Any thoughts appreciated, Thanks.
 
Watch for coolant loss, but with the bad water pump being replaced and the hose leak fixed you should be fine.

How many miles do you have to drive before adding a quart,1 between every oil change?
You need to do a wet/dry compression test and a leak down test to determine what the rings and valves are like before you bother with r&r valve guide seals. You could go through the expense for very little gain. At 200k on the clock, I would be inclined to agree w/ the mechanic you spoke to - just run it for now, and plan the complete rebuild for the next 200,000.
 
Pull an oil sample and look for coolant in the oil. Coolant in the oil is a quick way to ruin engine bearings. A oil sample will let you know what else is going on.

Smoke on startup with an engine your age and miles - likely valve guide seals or guide wear. The early 5.3's also had cold piston slap due to sloppy production tolerances - a overhaul would get better clearances as far as oil consumption. GM says not an issue because it would have cost GM a lot of money to correct and you already got 200K out of it.

Jasper is overpriced and not very good of a reputation.

How much is your rig worth and how much would it cost to replace it with something else? Then you can look at cost of redoing an engine and see if it is worth it. After all you have 2 lifetimes out of the engine and the rest of the rig now. Local rebuilder that you can take problems to is a good idea. Check their BBB and online ratings before going there.

Above all if the oil sample is good - adding oil is cheap. At the point the kittys foul out and plugs also foul out is when you need to worry about oil consumption. Otherwise keep an eye on the dipstick and add as needed. Emissions test failure may also doom a worn engine to a rebuild or replacement. Otherwise run it and get every last dime out of it. Till it $50's and $100's you to death at the parts store.
 
Do local auto parts store sell a oil sample kit or do I need to send it somewhere?
Because of low mileage put on truck each year that has me trying to keep it on the road. Assuming the heads aren't cracked. I agree the oil sample will be the best way of seeing now that WPump is fixed.
I went and put new rubber on it today, so I guess I'm stuck with trying to stay on top of things. I would be willing to spend $$ to replace heads if needed.
Mechanics say the rig is pretty good all in all, that's reassuring.
Thanks for all your help and advise
 
New rubber fits on newer rides... Used tires are found on CL all the time to roll things down the road or to a scrap yard. Don't corner yourself into a black hole for parts money. Hopefully you are good to go, but, here is some peace of mind:

Quick for a 1 time deal:
http://www.blackstone-labs.com/free-test-kits.php

I use a cheaper local place and get like 10 packs or so:
http://www.laboneinc.com/

Are you doing short trips or possibly a stuck open thermostat? This could cause moisture to build up in an engine. So could a restricted or INOP PCV system. With the miles Cokeing plugs up PCV systems solid. A area to check out if you haven't already.
 
I'm back with need for advise. Update to present, Had WP replaced and pressure tested, all went well, no external leaks, etc. Truck ran well, NO coolant loss for about 1 month or so. Now I'm losing coolant every 2-3 day's, light on dash, when cool tank is low. Took truck to shop today, pressurized for 2 hrs, they could find no external leaks. They took oil sample which I plan to send to Blackstone for testing. Garage mechanic is now convinced I have a internal problem, ie. cracked heads. When he pulled oil sample he said oil looked abnormal.

So....I like this truck and need to know if pulling this engine and taking to local rebuilder is best and having it re-built or can I get a Junkyard engine with hopefully low miles AND no bad heads? What years 5.3L engines can I ask for and if they are newer can I deal with the crankshaft issue as others have said needs changing.

My plan is to just it run it till it blows, doesn't much matter at this point, unless it helps to preserve the block for re-building.

Thanks for any thoughts or advise you can give.

Actrac
 
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