Help, cooling system not circulating

[mcs3675]

I just bought a 1999 vx, and the temperature gauge goes from normal to hot, and back! It keeps this up, and i dont know what it could be? Ive replaced the water pump, thermostat, radiator, and all hoses! Still same symptoms, any ideas? Air in system, or is it head gaskets?
Ive awalays wanted a vx, but im regreting this purchase everyday!
Please if anyone has any ideas, and thank you in advance!

Marcus

[Triathlete]

Do you have any antifreeze leaking from anywhere? If not have you checked to see if the radiator is clogged?

[mcs3675]

No leaks, brand new radiator installed today

[PK]

Do you have access to a Scan Gauge or similar to connect to the ECU??
Might be as simple as a faulty gauge, or faulty sender unit??

PK

[Makocross]

You have seemed to have checked all the normal things. Get or buy an infrared thermometer (cheap at harbor freight) and check to see if the temperature really is going up and down. Pick several spots on the engine and radiator to read and see if the temperatures go up and down with your gauge. If the engine temps are staying the same then it is the gauge or sender. If the engine temps are going up and down some one else here will come up with brilliant solution
Mike

[mcs3675]

Scan tool confirmed what the gauge says, its like the thermostat isnt opening, but two faulty stats seems unlikely! Also when the gauge goes to hot i lose heat! The top radiator hose gets hot, top of radiator is hot, bottom hose and core of radiator stays cold

[Makocross]

It seems like there isn't water flow to the radiator. Easiest thing to do is take the thermostat out and see if that makes a difference. If it doesn't then the water pump is bad or there is blockage. Just because it is new parts doesn't mean they can't be bad.
Mike

[mcs3675]

I was thinking of removing the stat tomorrow, but this thing is a pain to work on!

[HeckaTrebeka]

I know that you just changed the thermostat, but it might be a faulty thermostat... I've seen many times in many different cars a freshly installed thermostat fail and give the same symptoms that they had to begin with. Does the temperature change if you're more/less aggressive on the acceleration?

[mcs3675]

It doesnt matter how aggressive it drive, it acts the same, i dont want to drive it to far, im afraid it might get to hot! It stays normal not moving, went from idle to 3k rpm for 45 minutes to night and the temp stayed in the middle! But the radiator and lower hose never warmed up

[VX KAT]

Don't know if you've seen a few of the recent threads on here about temp/overheating issues. Many owners have had problems recently.
Many had done all the things you've done, but still had problem. A few found it was the fan clutch. Also, I recall some saying some of the non-OEM parts were pretty crappy, and they ended up replacing again with OEM.

I know these are long theads, but there's a ton of info in them.
Hope it helps you solve your issue.

http://www.vehicross.info/forums/showthread.php?t=23039&highlight=ron+davis

http://www.vehicross.info/forums/showthread.php?t=20543&highlight=ron+davis

http://www.vehicross.info/forums/showthread.php?t=22745&highlight=ron+davis

http://www.vehicross.info/forums/showpost.php?p=260573&postcount=5

[HeckaTrebeka]

If the hoses are still cold, I would think that's further evidence that the thermostat isn't functioning properly. If one part of your cooling system is cold but the other is hot, then there has to be an obstruction in the cooling system which is the reason I think it's the thermostat.

[Y33TREKker]

Did you try replacing the radiator cap along with all of the other items you mentioned, (or did the new radiator include one?). If the cooling system isn't kept properly pressurized, all of the hot coolant from the system will simply rise quickly to the top of the radiator because it's boiling. A properly functioning radiator cap that keeps the system pressurized will keep all of the coolant in a liquid state though.

It's also important to ensure that no air pockets formed during the coolant filling process.


Fill the coolant slowly with the engine off
When the radiator is full, then fill the reservoir to the "Max" mark
Install and tighten radiator cap
Idle engine for 2 to 3 minutes
Stop engine, reopen radiator cap (Carefully!! Hot!!, and refill coolant level if low
Tighten radiator cap and warm up engine at about 2000 rpm
Set heater to highest temperature position to allow coolant to circulate into the heater water system
Make sure thermostat is operating (radiator hoses should get hot)
Idle engine for 5 minutes, then shut off
Allow engine to cool, remove radiator cap, and refill coolant level if necessary

I don't know if I've ever seen a fitting on or near the thermostat housings on a VX that allow a person to burp the cooling system when adding coolant (the engine on my car has one), but if a cooling system is filled too quickly and air pockets form in the cooling passages, overheating can occur. That possibility and a faulty radiator cap are my first two guesses anyway.

[bigblock8396375]

I'm having the same problem,but I have excessive pressure in the cooling system. Hoses very hard and pressure is releasing into overflow tank. Hose going to thermostat cold,other hose hot. Temp gauge up and down, heat goes hot and cold. Took out thermostat (was new) ran with no thermostat same issue. Thinking it's a headgasket.

[FenderBender]

I have heard of people installing thermostats upside down. Not sure if one can on a VX? Just throwing it out there.

[mcs3675]

Its the headgaskets

[Y33TREKker]

Well, it sucks that you had to tear it down that far, but it's always a good feeling when you definitely determine what the problem was. Hopefully it'll be good to go for at least another 100k once it's all back together.

[mcs3675]

Well ive had it for less than a month, but as soon as its back together it going on crraigslist, ive had my share of isuzu

[Dmitrikr]

Just my thoughts - overheating sometimes cause by poor t-belt tensioner. waterpump has smooth pulley and if there is not enough tension - pulley/belt slips mostly when system build up pressure. happens on one 3.2 rodeo I was working on, happens on couple audi's v8 a6 've working on. after replacement tbelt and tensioner(OEM) everything was working fine.

[Chopper]

too bad mate.....mine's been a loyal companion for 11 years now. Never a hiccup.
You had to know any 13yr old vehicle (likely owned by multiple people) is not a good or likely candidate for trouble free daily driving....not straight outta the box anyway. Or you do now..... 13yrs= hobby car
Sort 'em out a bit....they go a couple hundred thousand miles, no sweat
Like the ads say....your results may differ:grino:

[mcs3675]

Well my 1996 toyota tacoma comes to mind, 222k miles and i had to replace a starter, and it wasnt a 3 hour job

[unchboy]

Theres a fail-safe thermostat at Oreilly's you might want to try.

[evillecutter]

Well my 1996 toyota tacoma comes to mind, 222k miles and i had to replace a starter, and it wasnt a 3 hour job

my starter has been going out on my vx - have to take the friggin exhaust off to get to the damn thing p.i.t.a. - in 9 months ive put over $2k into my proton (bought it for 6k) but when i look at my other options in that price range even after all the fixin i still want to keep my vx - hard to find any decent used car 13 years old for less than 10k that doesnt need a few grand in repairs - ...then again if it wasnt for this site and all the help and suggestions of its members i probably would have sold it long ago

[Chopper]

There very well may be another old Toyota in your future then, my man.
Good luck.....whatever way you go

[Y33TREKker]

Yeah, just when a person starts to consider Japanese engineers as thorough and forward thinking in their design processes, they then develop vehicles that either need to have the exhaust removed to change a starter, or part of the intake removed to change the back three spark plugs (late model Toyota Avalon I've recently experienced).

[HeckaTrebeka]

Well ive had it for less than a month, but as soon as its back together it going on crraigslist, ive had my share of isuzu

No offense meant here, but you really shouldn't base your opinion on all Isuzus or even Vehicrosses just from one bad experience on a vehicle you've had for only a month and don't know the whole history on. That shows short-sightedness and a narrow view.

All car manufacturers have vehicles that go bad, especially if people haven't serviced them within manufacturer specifications. So, to say that you're done with all Isuzu vehicles - or even just the vehicross - because the head gasket needs to be replaced, shows that you aren't willing to work on any vehicle at the slightest inconvenience to you.

Maybe you got a lemon or just a badly beat up car. If you want to stick with it, then we're here to help. If not, go ahead and sell the VX. Either way, this is a forum about the capability and awesomeness that is the Isuzu Vehicross and we don't really appreciate when people come into the forum and start bashing on a vehicle that we all think is cool.

Again, this isn't meant to make you angry or to bash on you personally. I just want this to be a chill forum where we can all help each other out. :)

[mcs3675]

Well finally got it back together, id say its fixed, no overheating! The problem wasnt entirely headgaskest, but warped heads, had them checked and they did need milled! So if your doing headgaskets save yourself some headaches and have your heads checked

[bigblock8396375]

Thanks for the "heads up" no pun intended! I'm in the same boat,I was just going to do gaskets, but now I'll check the heads. What brand of gaskets did you use? Thanks bigblock

[VxSport]

I am glad to hear that you solved your problem. Hopefully, you will take a few weeks and drive it. You may have purchased a project vehicle, however I am one to tell you they (Isuzu's & VX) are very reliable vehicles.

I have owned 7 Isuzu's since the first one purchased in '93, add up all the mileage and I am over 700k in a Zu. And yes I have a Vx in the garage (Daily driver) and a restore vx next to it, and a chevy and toyota in the driveway.
Give it some time, if you can. Something drew you to your vx. Many members have gone to the extreme to aquire their Vx's. We are all here to help, this forum is truely like no other.




Well finally got it back together, id say its fixed, no overheating! The problem wasnt entirely headgaskest, but warped heads, had them checked and they did need milled! So if your doing headgaskets save yourself some headaches and have your heads checked

[evillecutter]

ive said it before and ill say it again: you dont choose a vx - a vx chooses you

[JHarris1385]

I just followed this process and still have a lot of air pockets in my coolant. I noticed once I shut off the engine and popped the radiator cap off there was bubbling in the overflow box. I may have gotten a half gallon of juice in her.


Did you try replacing the radiator cap along with all of the other items you mentioned, (or did the new radiator include one?). If the cooling system isn't kept properly pressurized, all of the hot coolant from the system will simply rise quickly to the top of the radiator because it's boiling. A properly functioning radiator cap that keeps the system pressurized will keep all of the coolant in a liquid state though.

It's also important to ensure that no air pockets formed during the coolant filling process.


Fill the coolant slowly with the engine off
When the radiator is full, then fill the reservoir to the "Max" mark
Install and tighten radiator cap
Idle engine for 2 to 3 minutes
Stop engine, reopen radiator cap (Carefully!! Hot!!, and refill coolant level if low
Tighten radiator cap and warm up engine at about 2000 rpm
Set heater to highest temperature position to allow coolant to circulate into the heater water system
Make sure thermostat is operating (radiator hoses should get hot)
Idle engine for 5 minutes, then shut off
Allow engine to cool, remove radiator cap, and refill coolant level if necessary

I don't know if I've ever seen a fitting on or near the thermostat housings on a VX that allow a person to burp the cooling system when adding coolant (the engine on my car has one), but if a cooling system is filled too quickly and air pockets form in the cooling passages, overheating can occur. That possibility and a faulty radiator cap are my first two guesses anyway.

[tom4bren]

J,

It's not uncommon for the radiator reservoir to boil when an engine overheats. That's probably what you're seeing (not trapped air in your cooling system). Even if there is another problem with your cooling system, you need to replace your thermostat. If your engine overheated to the point of boiling your antifreeze, your thermostat is almost certainly cooked.

My recommendation is to get your radiator professionally flushed, replace the thermostat (or better yet, removed from OEM location and put in one of those inline thermostats that deermagnet posted about). Try running the engine again & if it still overheats, then it may be time to replace your waterpump.

[JHarris1385]

Was the above the best procedure to filling my radiator? I flushed and ran some gasket leak repair in it.

[tom4bren]

Was the above the best procedure to filling my radiator? I flushed and ran some gasket leak repair in it.

That would be the procedure for a 'problem' car. Normally a cooling system is self purging so you wouldn't have to go through all of that. You'd just add coolant as needed. If for some reason your particular engine is overheating, then Yah, the above procedure should be followed to eliminate the variable of trapped air in the system.

Keep in mind as well that the 'gasket leak repair' that you added could clog some of the tubes inside your radiator if you already had a corrosion build up. That's why I said that you should probably have your radiator flushed (to eliminate that variable). A garden hose flushing will probably not help in this situation.

[Y33TREKker]

Was the above the best procedure to filling my radiator? I flushed and ran some gasket leak repair in it.
It's based on the filling procedure taken from the Isuzu manual, and not necessarily just for vehicles with possible overheating problems. The main idea behind it is that overfilling any cooling system too quickly can cause air pockets, which can cause overheating if they're not eliminated.

[tom4bren]

It's based on the filling procedure taken from the Isuzu manual, and not necessarily just for vehicles with possible overheating problems. The main idea behind it is that overfilling any cooling system too quickly can cause air pockets, which can cause overheating if they're not eliminated.

We'll have to agree to disagree. On most cars, as long as there is coolant in the reservoir, normal driving will allow any air in the system to go into the reservoir and be replaced with coolant the next time it cools down. If that ain't happenin, then there is a design flaw or there is something FUBAR in the system. AFAIK other than the PITA thermostat replacement, we don't have any design flaws in our cooling system that would cause trapped air pockets.

I'm not disagreeing that it's what's recommended by Isuzu ... or even that it's not a valid process. It's just way over the top for regular maintenance.

[Y33TREKker]

We'll have to agree to disagree. On most cars, as long as there is coolant in the reservoir, normal driving will allow any air in the system to go into the reservoir and be replaced with coolant the next time it cools down. If that ain't happenin, then there is a design flaw or there is something FUBAR in the system. AFAIK other than the PITA thermostat replacement, we don't have any design flaws in our cooling system that would cause trapped air pockets.

I'm not disagreeing that it's what's recommended by Isuzu ... or even that it's not a valid process. It's just way over the top for regular maintenance.
Agree to disagree then, since the process listed was simply meant to minimize the chance of any air pockets forming during the coolant refilling process, not the steps required to check the coolant every time a person wants to check the coolant.

[tom4bren]

Agreed - we're both too bone headed to give in:)

[Y33TREKker]

Agreed - we're both too bone headed to give in:)
How can you say that when we've not even been talking about the same thing? ;)

[JHarris1385]

I am riding with a jug to work tomorrow to see where I am at after a 10 mile drive.

1/2 gallon or so in the radiator and filled to the max line in the res. tub.


I flushed with a prestone product and then put some head gasket repair in (did not work) and then rinsed her out with the hose and refilled with the amount above.

Looks like I need a professional flush, and a thermostat replacement.

Might as well do water pump, timing...etc while I am in there. Should be an adventure!

[EVO]

Not very likely but I have had the misfortune of installing two bad thermostats!! Drove me nuts!!