High Mileage Suburban - Problem areas

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Jan 23, 2003
ON, Canada
I am going to look at a 1993 Suburban 1500 2WD, 350TBI, TH700R4 with 166K miles on it. The truck has had two owners, and it seems the seller has taking good care of it, having detailed service records. It is on the original engine and transmission, and the body is rust free (a big selling point for me). What problem areas can I look for on these trucks? I know these TBI engines are good for a lot of miles, but I am always unsure when they are somebody elses miles. The current owner says he did 3000 mile oil changes, and he claims it uses a quart during that interval. I know the transmissions on these trucks are known to fail, but it does have a auxillary cooler, had regular filter and fluid changes, and was rarely used for towing (an 18' boat). It has rear heat, and he figures the lines are starting to clog as the output has been low. Any input is appreciated, especially those who have owned a Suburban from this vintage. I'd hope this truck would last to at least 250K without many major repairs.
My fathers 93 Suburban has 410,000KM on it and we just had to to the regular stuff. No engine; no head gaskets, no intake gaskets, no O2 sensors, no transmission problems, no nothing! Just pads, shoes, sparkplugs, few oil changes, We did have to replace the thermostat. Its the best vehicle he ever had. He had a 88 Suburban before this one that hit about 360,000 but that one had 2 transmissions and a second engine and a rad put into it before we junked it. Only thing wrong with the 93 Suburban right now is the antilock quit working and I just never got around to fix it yet. The antilock quit working just after he got it stuck. The computer code says that it is a simuntanious failure of both front sensors. So the deep snow must have torn the wire bundle where they go into the cab. So that is not the fault of the Suburban. It is the same as yours. Burgandy. What problems can you look for? I dont know.
Frankiee, thanks for the response. How did the suspension and front end on the '93 hold up over all those miles? What about the fuel pump, did that ever have to be changed, and if so how many times?
The company I work for has bought MANY of the mid-90's Suburbans (used, mostly with 100k+ on them when we bought them). This is usually what was needed: Tires Brakes Windsheild wipers/washer fluid Radiator Oil Change Air filter Fuel filter Lights all the way around Front end alignment And usually, within 10k miles, a transmission. After that, usually brakes, but they run pretty well, even with employees driving them all day, everyday, idling a good bit.
Originally posted by thooks: The company I work for has bought MANY of the mid-90's Suburbans (used, mostly with 100k+ on them when we bought them). SNIP
What kind of business was this?
Originally posted by TomJones76: What kind of business was this?
Engineering/Surveying/Outside Plant staking/construction
Father got is at about 140,000KM How did the suspension and front end on the '93 hold up over all those miles? 1 ball joint. 2 tie rods. 4 shocks. No springs (that we know about I forgot about the fuel pump in the tank, 2 of those. As far as I remember it has rear ac and heater core which we bypassed because of failure. 1 heater fan. It has a oil cooler for the trans and the engine oil in the rad. I think it is a 3 or 4 core rad. Rad was replaced once by us. I think the big thing is the big rad in it to be able to handle the temps of the coolant and the oils. He says he gets 23 mpg and 27 on the highway. Replaced the starter not to long ago and an alternator last year. Sounds like a lot when I am putting it down right now but a lot of that was just in the last 2 years. Up to above 300,000 I don't remember if I ever had the hood up except to change the oil. Father bought it off a dealer who said that the one prior owner was a minister that used the vehicle to carry church members around. We believe it.
Intakes, tranny problems. But since you mentioned they changed the fluid and filter a couple times, I bet the tranny should be good.
I went and looked at the Suburban today. It was in pretty good shape overall. The body was very solid and still had original paint. All the electrical accessories worked fine as well. The 350 fired up very quickly, and had no blue smoke. The transmission fluid was nice and red, and I saw the transmission cooler that the owner had installed (stacked plate thermostatically controlled). The transmission went into gear quickly with no hesitation (turns out it's a 4L60E). I also checked the RPO codes and it has the 3.42 gears limited slip, which should be a little better for fuel mileage than the optional 3.73. I didn't have a chance to drive it other than in the yard, as it is unplated right now. The owner will take care of that so I can drive it at speed and make sure the transmission works well, and there are no rear end noises or other problems. Another bonus is that it doesn't have the frame hitch or factory tow package, so it is unlikely that it has towed anything of serious weight. I still have to go over the service records, but it definitely appears to have been well taken care of. Even the interior is still in great shape, and it was a family vehicle. Thanks everyone for the input and keep the advice coming. What kind of fuel mileage are you guys getting with these trucks? I see the 2WD was rated 13 city, 17 highway by the EPA. I'd be happy if I get the 17 MPG highway.
In tank fuel pumps seem to be a common GM weakness after 100K miles. A cooled, serviced tranny can last well past 200K.
Sounds similar to the '95 GMC K1500 I bought last year. It has around 169k miles now. Mine has a problem that comes and goes. Sometimes it has bad idle and when cruising steady state on the highway, it sometimes loses power then has to downshift to rev up the RPM's. I am still trying to track the problem down. It is either a vac leak, the TB gasket b/t the manifold is leaking, or needs a fuel pressure regulator. Check to see if the 'burban does it also. The previous owner only replaced the fuel pump, P/S pump, radiator hoses, and that's it. I had to do the 1st trans service, 160k+ miles on original fluid! Those with GM truck transmission failures usually did not service them and burned them up either mudding, heavy 4x4 action, or hauling butt when towing. If you buy it, go ahead and drop/clean the trans pan and install a drain plug like I did. NAPA has them for $6. Other than that, those are real solid trucks. All I can foresee is front rotor replacement, and regular fluid/filter services. Good luck.
We have a low mile '87 (116k) that the boss bought for it's utility. I have to admit that if you need the space and utility, a Suburban it tough to beat. From my end, mechanically I am unimpressed. The 350 is underpowered and like Willys', gets 12 mpg. Oil leaks and valve seals have been a problem somewhat helped by an Auto R-X treatment. Rust on '91 and earlier is a serious problem. It seems later models are better.
I would not use anyhing less than a 10W30 for the engine and ARX it to clean the piston rings and internals; use Amsoil Ea series filters for oil and air. Pablo can ship them to you very quickly. Problem areas I have had are: Fuel filters - change ASAP if not noted in maintenance log, Tranny - change fluid to Dexron III(H) ASAP (at least a Blend or partial synthetic) and run some LC with refill, replace filter. Add EXTERNAL cooler if not so equipped. Change TC fluid to MTFGlide. Vacuum leaks in engine compartment - replace fittings and hoses to and from TBI. Brakes - My sub liked to eat brakes. Replace rotors, pads, and brake shoes. U-joints, in my view, undersized for job. Replace with greaseable U-joints. Replace rear differential fluid with synthetic 75W140. Chevy differentials are weak in my view, so no mineral oils, only synthetics. Replace PS fluid with DexronIII(H). Have front and rear AC checked. Rear Air biggest problem area. Replace Water Pump and Alternator, if not already replaced; another weak area. Last Burb I had engine went to 325,000+ with only oil and filter changes. Check distrbutor/ rotor cap and timing on distributor if so equipped. Replace distributor if timing is too variable. [ April 10, 2006, 01:49 PM: Message edited by: MolaKule ]
On the brakes point, it's important to adjust the rear shoes routinely. The self adjusters don't work very well in these GM's and that's the reason lots of people report high front brake wear...because they have no rear brakes. I've replaced my alternator and water pump on my 98 k1500 as Molakule mentioned. I can get 22mpg highway with my vortec 350 4x4 extended cab...bigger tires...cruising at steady 75 mph.
Also, I've done the intake manifold and fuel pump(which I think was a bigger problem on the vortechs). I'd also do the fuel filter once a year. When my fuel pump failed, the filter was clogged after 30k miles. I just did mine at 25k miles and it took a great deal of effort to blow through it compared to the new one. I guess it makes sense because of the huge number of gallons of fuel that run through these trucks. I think this is why so often fuel pumps on these trucks fail. You'll also be irritated by interior and exterior door handle flat-out busting off on these trucks. I think I've replaced a total of 6 of these just on a two door truck. The dealerships says they sell them like McDonalds sells big macs......(not that GM changed the design or anything over a span of 12 years to correct this problem).
What we saw in our company was that we had failures with them in the first couple years of service (transmissions, alternator, A/C) after a couple of years they seem to go forever without needing anything other than routine maintenance. We had a few with close to 300K without any engine work. None on the original transmission though.
I bought the truck yesterday. It drives amazingly well for the age and mileage. I have driven trucks with half as many miles that don't drive half as nice. It just goes to show you how regular maintaince can make such a big difference. Now the big question, what oil to run!?! Actually, I am probably going to start off with Esso XD-3 10W30 HDEO and an Auto-RX treatment. After the treatment is done, I will probably switch it over to XD3 0W30. So many choices...
Thanks for the advice. I do plan on changing the fuel filter, air filter and inspecting all vacuum hoses. I just inspected the brakes today, and both front and rears still have plenty of life left. The fronts are almost like new. The waterpump was just changed as well as the lower rad hose. Molakule, why do you not recommend anything lighter than 10W30 in these engines? I live in an area that can get to -30 F during the winter time, so that's why I was considering running 0W30 year round. The Esso XD-3 is actually a thicker thirty weight, with something like a 12 CST viscosty at 100 C.
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