John writes:
How often should coolant hoses be replaced on older vehicles? And not just when they start to leak! Should it be based upon age, mileage, climate of operation, or what? For that matter, what about the other hoses conducting pressurized fluids, vapors and the like? We have guidelines for belts and serpentines, but hoses?
Sajeev responds:
Good question. I’d check coolant hoses at every coolant change interval, which also leads to the obligatory RTFM reference for the newbies. Squeeze the hoses (when cooled, obviously) and look for brittle, soft or cracked rubber. Maybe go to a parts store and fondle a new hose to make sure you know the difference between a good hose and a soft one that’s about to burst. Don’t be shy!
And don’t forget the smaller hoses feeding coolant to the heater (at the firewall), the water pump and your overflow bottle. Every hose is critical on a pressurized system, if one fails the whole thing goes kaput.
Regarding other hoses: like transmissions (I’m looking at you, various iterations of the Chevy Malibu) that don’t come with a dipstick, other hoses are made to last “the life of the car.” Automotive leasing aside, that’s a crock. You will have to address these hoses after 8 years or 100,000 miles. The most common hose failures surround emissions equipment like the PCV system, and miscellaneous intake manifold mounted vacuum lines/junctions that cause “Check Engine” lights and poor performance.
And from what I’ve seen on the forums, these trouble codes (engine bank lean codes, specifically) are a ruthless/ignorant mechanic’s wet dream: there’s money to be had by throwing parts (and labor) to chase down a code instead of ruling out the most obvious problem. So do yourself a favor and inspect all hoses when you do a tune up, or change an air filter.
NN writes:
My 1998 Chevy Blazer (ZR2, 4wd, 5-speed) with ye olde 4.3L pushrod V6. 145k on the odo with recent radiator, water pump replacement. I had the coolant flushed and switched from the old Dexcool to the regular stuff. I noticed this past fall as the weather cooled that the engine was never really warming up…staying cold all the time, so I put in a new thermostat, figuring the old one was stuck open. Then the weird stuff started happening…sometimes my new thermostat wouldn’t pop open until the engine temp got well above 210, and I got a little nerve wracked.
It’s not the gauge… feeling the upper hose and seeing it was cool told me that it wasn’t circulating. Eventually the t-stat would pop open, but not at a consistent temperature; and well above the halfway mark where it should open. At the same time, there was a small coolant leak coming from somewhere I couldn’t detect… I guessed the leak may be a bad freeze plug, and a bottle of Bars stop leak did the job and sealed the leak. I switched out the thermostat again thinking the first new one was bad, and that didn’t work-same issue. I then figured the reason the thermostat wasn’t popping may be a lack of pressure in the system so I got a new radiator cap. Since the stop leak and the new cap, I haven’t had the thermostat issue.
But the heater is still weak, which leaves me with a lack of confidence. Did I really fix it with just a new cap and a bottle of stop leak? Could it have been a lack of pressure due to a worn cap or small leak that led to the delay in the opening Thermostat? Or could it have to do with something else (heater core?) that I’m not considering? I’m not sure I’m out of the woods yet so any other ideas would help.
Sajeev reponds:
Nice detail in your write up. I think you are out of the woods: the radiator cap was the final solution to your complex problem. For paranoia’s sake, check your overflow tank for stress cracks. Depending on the vehicle, an overheated (plastic) reservoir can lose its marbles and leak, which leads to engine overheating. Or on an I-6 BMW, a warped head and a $13,000 repair bill. Hot damn!
The heater is a mystery to me, perhaps it was clogged and the stop leak plugged it shut? I’ll keep my fingers crossed that replacing the heater core doesn’t involve removing the dashboard in the Blazer. I’m doing that right now and it truly sucks.
[Please submit your mechanical quandaries to sajeev.mehta@thetruthaboutcars.com]
I’m not so sure… I’ve broken plenty of things that didn’t need to be fixed :rolleyes, this could be something else to file in that cabinet… and only had one hose go on my so far in eight years and, at the time, it wasn’t the oldest vehicle I’ve owned.
These days my answer is to leave well alone!
Sajeev–thanks for the posting and response! And yes, changing the heater core does involve dropping the steering column and taking out the dash…I did it on my last Blazer and it really sucked, so I’m trying to avoid at all cost.
update–I’m not out of the woods yet on the thermostat issue, as the same thing happened to me again this week…not popping until well past 210. I will try something new today that might be of interest to you…drilling a small hole into the thermostat. I read on a forum that small blocks (which the 4.3 essentially is w/2 cylinders lopped off) can get steam trapped in the thermostat housing which prevents the coolant from getting to and opening the thermostat. That sounds like exactly what’s happening. Short of pulling the thermostat, I read on a forum that you can drill a small hole in it to let the steam escape. Sounds logical, let’s hope it works.
Hey what car does the engine compartment in the picture belong to ? It looks nice and simple and economical, must be from the 60’s.
In my part of the world the heater is crucial.A few things I’ve picked up:All hoses, look at them,feel them [when cold]smell them.Take the time to look at your parking area for leaks.
Hoses are cheap and generally easy to change,so when in doubt change em.
Sajeev is coreect.Stop leak and Barrs are an invention of the devil.Nothing will f–k up your heater core faster.
I’ll venture a guess, pleiter, that it is an updated British product of some sort based upon the head and valve cover. The yellow coil on the fenderwell is not a stock piece, but my experiences with British cars indicate that upgrades are necessary from the original Lucas Prince of Darkness factory equip. The chrome airbox covers a non-SU carb and the block looks smallish.
Spitfire? Healey Sprite?
I am no Chuck Goolsbie but I think Barry is right. I would say MG.
I think its a 1940s era (made until early 1980s) motor- push rods, with intake and exhaust on same side and “not a hemi”.
Horrible old tech but major fun nonetheless and intensely desirable.
The white plastic thing on right fender looks oddly modern. And out of place if its a coolant overflow tank.
It looks like an ‘A series’ engine from BMC/British Leyland.
These things have been knocking around since the early ’50s upto as recently as 2000, in displacements ranging from ~800cc to 1275cc (sometimes bored out to 1360/1380cc). This one appears longitudinally mounted, so ruling out the Mini, Austin/Morris 1100/1300, Allegro, Metro & Maestro and their various derivatives, but leaving practically every other small-medium sized car they made in that period.
If I had to guess, I’d say MG Midget.
@NN
You Blazer is an easy diagnosis. Years of Dexkill (a.k.a. Dexcool) have sludged up the passageways in your heater core. It is an all too common problem with GM cars, especially the ancient 4.3L engine which was never designed to properly handle Dexcool and has the unfortunate side effect of frothing the coolant. Due to the composition of Dexcool, frothing air with the coolant creates nasty sludge.
So, the solution to your problem is relatively simple.
1. Go to the parts counter at any GM dealership and get the GM radiator flush additive. It MUST be the GM part, not the regular “Prestone” flush you get at the auto parts store. YOu can however buy the regular Prestone flush kit to get the parts you need to properly flush the system (just not the flush fluid).
2. Follow instructions for flushing the coolant system, making sure you have your temperature control to maximum hot.
3. Refill with green coolant and test heater.
IF you still have insufficient heat or hear gurgling from the heater core, then a more drastic procedure is necessary. You will need to disconnect both heater core lines in the engine bay, and find a way to hook your garden hose into the lines (can be ghetto) to flush the system. Then stand back as nasty gunky water comes out the other side. Keep flushing until water runs clear.
As for your leak, it is likely the upper or lower intake manifold gasket. Chances are, the coolant is dripping and evaporating before it gets to the bottom of the engine, making diagnosis a pain (look for orange or green crust buildup).
I can’t tell you how many times this problem has come up at work (Delphi) on our internal newsgroups, somebody asks the question at least once a month.
I highly recommend switching all GM cars over to the green stuff from Dexkill as soon as the powertrain warranty runs out, especially pre-2003 vehicles which seem to have the hardest time with it.
The high temp reading, followed by a quick drop in the gausge reading is indeed caused by no flow then BAM, t-stat opening. To eliminate this effect, most t-stats have a factory provided hole in the ‘stat’s flange, with a little jiggly metal thing in it. This allows a very small amount of flow when waiting for the stat to pop open, which eliminates the condition you describe. Factory brand ‘stats usually have this feature. Many aftermarket units do not. A common problem with this jiggly thing is that it gets gunked up with the excess permatex that too many “wrenches” use. When the ‘stat housing is pressed to the engine, all that excess oozes out, and some of it can easily plug the jiggly thing. Change your ‘stat. And remember all GM owners, DEX KILLS.
Regarding the time interval for hoses and belts, I change all of them, all at once, every 7 years. Change the t-stat, all heater hoses, and take a careful look at any hard lines that may be rotting out or, in the case of plastic parts, getting ready to split. Check any trans cooler lines and vacuum hoses at the same time. I’ve kept most of our extended family’s cars going for years. We typically go for 200K or so without engine dissassembly of any kind. I’ll add timing belt concerns for us “high milers.” Remember, modern engines are really durable provided that they DO NOT OVERHEAT. Aluminum engines, especially aluminum heads on iron blocks do not take kindly to high temperatures. One modest overheating is all it takes to take out the head gasket. Today’s engines are not like a 1972 455. Changing all this stuff means that you can take old cars on long road trips with minimal worries. Years ago I used to drive an old K car to the slopes with well over 200K and never ended up on the side of the road. If a crappy car like that can go the distance, today’s cars should have no problem.
Worked in a garage for seven years then in the Engineering Dept. of a major Class 8 truck manufacturer. I do most of my own work.
Coolant maintenanance? Flush and refill with the proper 5-year coolant every five years. Radiator and heater hoses every 10 years. Gates Green Stripe is the only stuff I will use.
Vacuum hoses? When the ones near the manifolds start to crack I’ll replace all 6-7 doing one at a time. They last 5-7 years.
Friend bought a top Benz at half wholesale as it ran like crap. Replaced the vacuum hoses and sold it for a staggering profit.
Excellent advice all around!
NN, I second the super-mega coolant flush to get the dexcrap outta there. And maybe you should install a “fail safe t-stat” with the hole already drilled in it?
http://www.motoradusa.com/products/failsafethermo/index.html
And one other thing: if you bought a radiator cap with a quick release handle (normally seen on caps that go on the radiator, not the tank) those are known for failing much, much earlier than the conventional push/turn parts.
Someone correct me if I’m wrong, but I’ve also heard (regarding Dexcool) that the bearing seals in some GM waterpumps were designed with Dexcool in mind and since Dexcool isn’t as acidic/caustic as the green stuff that on some models using it can cause premature pump failure due to erosion of the pump seals. May be safer to use the Prestone “any color, any type” coolant. Although I can’t imagine it mattering on the 4.3 unless they used a different waterpump pre-Dexcool vs post-Dexcool introduction (CPI 4.3 was introduced in the early 90’s, well before Dexcool was standard fill w/ GM).
-also-
Dexcool and the green stuff are COMPLETELY incompatible and if you have the smallest amount of Dexcool left before filling with the green stuff you’ll get sludge.
We have guidelines for belts? What are they? I’ve never changed a (non-timing) belt as preventative maintenance. My buddy’s Suburban has 22 years and 200k miles and he still has original belts. The best thing you can do is to inspect your car regularly. Look at the hoses and feel the hoses. If the rubber is still good, leave it.
The best thing you can do is to inspect your car regularly. Look at the hoses and feel the hoses. If the rubber is still good, leave it.…
I wouldn’t feel good about that. Belts and hoses fail under maximum stress. A vehicle that has been used for short trips for 5 years, for example, may one day be caught in bumper to bumper traffic during a hot summer day, and the belt, under more stress than usual, snaps. That’s why a belt doesen’t break in your driveway. They are just too damn cheap and easy to replace to be eeking out the last bit of life. After 7 or 8 years or 100K miles, why take the chance? Sitting on the side of the road really sucks.
Doubletee, you are correct that you must flush all of the evil Dexcrap out of the system. Once you have captured the vast majority of the dexdeath, use a flush chemical and then allow water to flow through the system for a long time, making sure you include the heater core. Having forked over $700 to replace an intake gasket, I wouldn’t put that shit in anything I own.
@dubtee1480
Dexcool is an OAT coolant (Organic Acid Technology) and just one of many coolants which fall under the OAT category. The theory of mixing OAT with non-OAT causing sludging has never been substantiated. Mixing an OAT with non-OAT (traditional) merely reduces the service life of the coolant to 2 years/30k miles. The “mixes with all coolant” Prestone is OAT as well, but the chemical additive composition is different, which seems to be why people have good success with it.
@NN
I know you mentioned that you changed the radiator cap, which is very good. It is likely that your old cap was bad, which can accelerate the sludging process by sticking open and allowing air into the system. I would take Sajeev’s recommendation further and suggest picking up the OEM thermostat from the dealer and make sure you install it with the jiggle valve up. Also, I would only use the factory radiator cap even though it may be prone to failure. Aftermarket caps may not be rated to high enough pressure.
Reverse flush the system with a flushing tee and water. Most after mkt caps have the pressure limits labelled on them. Bars Leak, the brown goop, was used a 1/2 bottle at a time to manage the heater core leak in my 86 528e. I change the accessory belts when changing the timing belt at 60k mile/4 yr intervals. Hoses get changed as needed. The 528e has a low coolant level warning light that will alert you to a leak. When I take the car on road trips, I carry tools, used hoses and coolant in my spares bin for such eventualities. Some of the hoses on my 21 yr old car are original and still in good shape.
fantastic responses and advice; much appreciated!
NN: one last thing to check is air on the system. Any airlock will result in the symptoms your describe. THe leak you have may be letting air in while the system cools down and produce an airlock on the next cycle.
Yes, I’ve been there. VWs have a very small hose from the head to the expansion tank to bleed air. When it clogs you get you exact symptoms.
ekaftan has a point — my ’97 Camaro (3.8l) had an air bleed screw in the top of the thermostat housing as it was a higher point than the radiator (may not apply in your case).
The Dex-kill is definitely “boon to bane” after the 50k mark…
I hope that GM has stopped using it, as, besides bankruptcy, DexCool in a new Camaro would be another reason to just say “fugeddaboudit”.
ekaftan : one last thing to check is air on the system. Any airlock will result in the symptoms your describe. THe leak you have may be letting air in while the system cools down and produce an airlock on the next cycle.
Yes, that is crucial. Run the motor (cool) without the radiator cap and with the heater on. Put that cap back on the second the coolant starts to overflow on the radiator or reservoir.
And like shaker said, many cars have another bleed point that you have to use, in this same manner.
Belts? The tensioner usually locks up before the belt does. Might as well do both at once.
I’m picky about belts, hoses, etc… Every three years. I just did this on my van. $38 for all hoses and $27 for a serpentine belt is cheap insurance. I’d rather do it in my drive way than hike to the nearest Autozone, then back to the van, to do it on the side of the interstate.