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Discussion Starter · #1 ·
Hi

For about 1 year I have been having problems with overheating. I have a few posts related to that and many have offered assistance. After replacing most everything (radiator, fan clutch, thermostats, hoses, coolant, etc.) I bought a combustion leak tester from NAPA.

You insert blue fluid into a tube and that tube fits where your radiator cap goes. If it turns yellow, you have a leak. If it stays blue you are ok. The directions just say if it turns yellow, nothing about staying yellow.

Mine turns yellow quickly, then slowly turns back to blue.:mad: I was expecting it to be like a pregnancy test and stay positive if it is positive. BTW, engine has 209K on it 3.4L V-6. Head Gasket was replaced under recall @50k.

Any recommendations, condolences,flamage?

If bad, do I
  • get a crate engine (from where?)
  • rebuild this one?
  • scrap truck?
Thanks
 

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What is it suppoed to detect, a leaking head gasket or something. If so run a compression check. Maybe all you need is head gaskets.
 

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Discussion Starter · #3 ·
What is it suppoed to detect, a leaking head gasket or something. If so run a compression check. Maybe all you need is head gaskets.
It detects combusion gas in the coolant. Could be from head gasket or some other problem. I can try to do a compression test this weekend.
 

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I figured as much. I think the only thing it could be is a head gasket so the compression check will not only confirm that but should isolate it to which jug.
Looks like you're in for yanking the heads in any case. May as well get a new timing belt, water pump, new fan belts etc. while you're in there since all of that shit is coming off anyway.
Which that many miles on the clock you'd want to do a lot of other stuff too. A valve job and if the hone in the cylinders is still good just add the rings and make a complete top OH out of it.
When you get the heads off, take a really close look at the webbing between the valves. They are very thin and if the truck has a history of overheating they may be cracked. Aluminum doesn't like getting too hot. If they are cracked, maybe it would be worthwhile to find a another engine unless you can find a very good welder that can fix them. You'd want to do that before the valve job. Toyota charges an arm and leg for just the machined head castings. An arm for one and a leg for the other.
 

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I have one of those testers at work...the fluid reacts with hydrocarbons which if you have a blown head gasket and or cracked head/block will be in the cooling system.

The fluid will turn yellow or green if hydrocarbons are present...and yes it does go back to blue after a while...
 

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Discussion Starter · #8 ·
So Dick do you think a head gasket is doable for someone who has never torn an engine apart before. The truck is semi-retired currently in the garage, so it is not like I have a time limit to which I need to complete the task. I have the service manual. I have just the basic tools and will need to buy more.

thanks
 

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Yes the head gasket is doable for someone who has the tools, time, and basic knowhow to fix an engine. Like Dick said begin by tearing down the old motor to assess what shape it's in. Most likely the head is cracked in the webbing, I found that it is more common than most of the people here think it is. A good place to locate new heads for cheap is clearwater cylinder heads (cch.com) I think? Mine had 140k when it was torn down and the bottom end was very nice (still had cross hatching in cylinder walls.) Definitely want to download the fsm from this site. Like was mentioned before have a wet compression test done to see if you will need rings.
 

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Discussion Starter · #10 ·
Finally getting around to thinking about maybe doing this this year. The truck has been garaged for about 4 years no, just driven once or twice a year to cylce some gas and pass emmisions testing.
 

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So Dick do you think a head gasket is doable for someone who has never torn an engine apart before. The truck is semi-retired currently in the garage, so it is not like I have a time limit to which I need to complete the task. I have the service manual. I have just the basic tools and will need to buy more.

thanks
I do not suggest trying to change the headgaskets as a first experience. Its not easy at all and you must have the right assortment of tools or you will end up beating the shit out of the truck cuz your pissed off as hell. Plus you have to make sure you diagnose and repair the cause of the leaking headgasket, or it will just do it again. With over 200k, youd be foolish to tear it down as far as heads off and not to do the pistons, rings, bearings also.
 

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Just do it man. The hardest part about the job,... is thinking about it. I just go done replacing my head. I have only done it twice in my life time. first time on a porsche and now on my 2000 tacoma. I have to admit,... it was easy as hell. At one point I stopped following the FSM. Its so straight forward. Remove everything and disconnect the wire harness. Very easy.

Just get little plastic baggies and a black marker. Bag all the bolts and everything you remove. Label what it is.

But before you do it get yourself a leakdown tester from harborfrieght. Its like $40. If you have a blown headgasket this will tell you.

Also,... you havent notice any oil in your coolant or vise versa?

You you do decide to get an engine try japanengines.com. I got my new head from there. 500 shipped.
 

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Your better off getting a motor from a 2000 and up. It's easier to put in a running motor, than hoping that the first headgasket that you do holds.
 

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Discussion Starter · #14 ·
I have not noticed any coolant in the oil or vice versa. I did fail a test where I put a test tube on top of the radiator and the fluid changed color, indicating I had exhaust gas in the coolant. The engine compartment does seem to have a anti-freeze stink, but I can't pinpoint any sort of coolant leak.

To the best of my knowledge I have never hit red on the temp gauge, but I have come close while idiling in traffic. Once driving again, the temp comes down. I have new had thermostats, fan clutch, radiator, etc.

Aside from a cracked head or head gasket, could the problem be something simpler?
 

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I have not noticed any coolant in the oil or vice versa. I did fail a test where I put a test tube on top of the radiator and the fluid changed color, indicating I had exhaust gas in the coolant. The engine compartment does seem to have a anti-freeze stink, but I can't pinpoint any sort of coolant leak.

To the best of my knowledge I have never hit red on the temp gauge, but I have come close while idiling in traffic. Once driving again, the temp comes down. I have new had thermostats, fan clutch, radiator, etc.

Aside from a cracked head or head gasket, could the problem be something simpler?
First of all,... temps gauges these days are dummy gauges. Which means the temp gauge doesnt flucuate to show the true temp of the engine.It goes from cold to warm. When engine is REALLY hot then it moves up towards red. When that happens you should pull over and shut your engine down.

When you run your engine super hot like that, pressure builds up in the cooling system. You could blow your radiator or blow a hose. Happened to me.

Even if you have a busted head gasket your engine should still maintain a normal temp as long as there is plenty of coolant in the cooling system. When you run low on coolant thats when the engine runs hot.

If you had a blown head gasket where you were leaking coolant,... it has to go somewhere. Into the oil galley, into the cylinder, or leaking exteriorly.

Into the oil galley:
coolant in oil

Into the cylinder:
Coolant in oil
white smoke from tailpipe

Leaking exteriorly:
You should see that, a wet engine or puddle on the ground

If your head gasket had a small area of failure and a little bit of coolant was leaking,... you would never even know about it. A small failure shouldnt keep your engine from overheating. As long as you have coolant.

Get the $40 leakdown kit from harbor frieght and rule out your headgasket. Have you tested your coolant temp sensor? Your cooling fans are working properly? If your fans arent working, while driving your engine temp will be fine. At a red light you will start to over heat. Your radiator is original? Are your radiator hoses warm when the engine is warm?
 

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Discussion Starter · #16 ·
One of my main symptoms is boiling coolant in the overflow tank, if that really is a symptom or maybe a misunderstanding on my part. The cap of the overflow tank continuing pops off and grime builds up in there. I suppose that could be oil, but I always assumed it was road dirt. When I am done driving, the overflow tank has boiling coolant in it.

The radiator is new and was purchased during my trouble shooting, as is the fan clutch, mixer valve, various thermostats, new radiator cap, upper/lower hose + the hose the the oil pump too I think. I have tried to solve the problem by throwing money into it. $40 for the tester thing will be well spent I think. The water pump has 25k on it.

The battery is currently dead so I just jump-started it. I do not see any white smoke. I don't think there is coolant in the oil either. I don't think I have oil in my coolant, or if so, it is very little - maybe 1/10 drop from a medicine dropper, not a tablespoon or anything like that.

I have not officially tested the coolant sensor. I will have a look at the service manual and try and figure that out. I also now have a non-contact infrared thermometer which is really cool.

thanks
 

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Lordy. Ok if you have boiling coolant when you drive then I wouldnt worry about temp sensors etc. That would only lead to a misleading temp on the gauge. Because of the fact that your coolant is boiling is a sure sign of true overheating.

how did you check for oil in coolant and vise versa? Did you drain both systems into a clean pan and see? You have to do that to get a good idead of whether or not either is contaminated.

Drain both systems and let us know. If you have a camera, use it. We would like to see. LOet the oil sit for a while so the coolant to float to the top. will look like floating bubbles or one huge bubble if theres enough in there.

From a complete coolant drain. When you refill how much coolant can you get into the truck? Less than normal? about the same? How much?

Does your coolant volume keep dropping? Are you having to constantly refill?

Another thing to check is to see if you pump is even pumping. Maybe its pumping but you have a clog somewhere and the coolant isnt making it totally through to the radiator to be cooled. Cooling systems are actually pretty simple. Pump > engine > radiator > back to pump.

From a cold start let your engine idle till warm/ hot. Back and forth feel the hose going to and from the radiator. They should both get very warm. They should also feel a bit firm too. Equally firm. When you drain your cooling system feel the hoses feel like when the system is empty. soft.

When you engine is warmed up do you have heat through your heater unit? Does your heater work? Is it really hot or not as hot? Whats the deal?

If you have a blown head gasket,... thats another problem. Wouldnt worry about that right now although I wouldnt wait to get the leakdown kit. Its cheap and one of the best tools youll ever own. OH WAIT! Do you have a compressor? If not then get a compression tester kit instead. Not as good as the leakdown kit but will tell you if your losing compression.

Focus on the cooling problem. just find out that coolant is flowing freely through your system. Thats the only thing I can tell you. Its a pretty simple thing.
 

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I read that you have been having this problem for a year. This before or after the pump change? have you taken the truck to a dealer to see what they think? what year is your truck?
 

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Discussion Starter · #19 ·
Lordy. Ok if you have boiling coolant when you drive then I wouldnt worry about temp sensors etc. That would only lead to a misleading temp on the gauge. Because of the fact that your coolant is boiling is a sure sign of true overheating.

how did you check for oil in coolant and vise versa? Did you drain both systems into a clean pan and see? You have to do that to get a good idead of whether or not either is contaminated.
I do my own oil changes and did not see any obvious changes in the appearance of the oil as it drained. I have not drained into a clean bucket but use a contained designed to catch, hold and store motor oil. I can get a clean bowl of some sort and repeat.

My anti-freeze is somewhat orange and green at this time but I do not see any oil at the top of the radiator. I assume the oil would float, but I never considered that the anti-freeze mix might be lighter than oil.

Drain both systems and let us know. If you have a camera, use it. We would like to see. LOet the oil sit for a while so the coolant to float to the top. will look like floating bubbles or one huge bubble if theres enough in there.
I will do, but it probably won't be until this weekend.

From a complete coolant drain. When you refill how much coolant can you get into the truck? Less than normal? about the same? How much?

Does your coolant volume keep dropping? Are you having to constantly refill?
I will do also and I did need to refill regularly when I was driving the truck.

Another thing to check is to see if you pump is even pumping. Maybe its pumping but you have a clog somewhere and the coolant isnt making it totally through to the radiator to be cooled. Cooling systems are actually pretty simple. Pump > engine > radiator > back to pump.
I suspected that maybe there was a clog somewhere but I had a hard time troubleshooting that. I remember trying to run the truck in the driveway with the top hose disconnected and it seemed to flow. I bought the engine block tester from NAPA and when the color changed, it seemed to be a done deal that there was exhaust in the cooling system and I stopped investigating the clog. (http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm)

From a cold start let your engine idle till warm/ hot. Back and forth feel the hose going to and from the radiator. They should both get very warm. They should also feel a bit firm too. Equally firm. When you drain your cooling system feel the hoses feel like when the system is empty. soft.

When you engine is warmed up do you have heat through your heater unit? Does your heater work? Is it really hot or not as hot? Whats the deal?
In cold weather, the heater does not work at idle, at a traffic light. As I drive the heater then blows hot air. This is another reason I thought I had a clog.

If you have a blown head gasket,... thats another problem. Wouldnt worry about that right now although I wouldnt wait to get the leakdown kit. Its cheap and one of the best tools youll ever own. OH WAIT! Do you have a compressor? If not then get a compression tester kit instead. Not as good as the leakdown kit but will tell you if your losing compression.

Focus on the cooling problem. just find out that coolant is flowing freely through your system. Thats the only thing I can tell you. Its a pretty simple thing.
I have a compressor and can get a leakdown kit. I also have the FSM from 1996.

As far as the cooling system being simple, I don't have a complete understanding of it from the FSM. I understand the radiator and the two hoses, one for cool water and one for hot. Hot is on top I think? From the bottom hose it goes into the water pump and into the engine. If there is a clog in the engine, how do I troubleshoot that? What happens when it goes into the engine? Does it go in the left and come out the right or the top?

I read that you have been having this problem for a year. This before or after the pump change? have you taken the truck to a dealer to see what they think? what year is your truck?
Truck is 1996 with 5VZ-FE
I think it may have started in 2006. Late in 2006 we were able to purchase another vehicle for our home and I semi-retired the truck. I have owned it since it was new in 1996 and have an attachment to it. A truck is useful to have. I have only driven it once and a while to cycle the gas and to go to the emissions station in Colorado in order to keep the vehicle registered and insured. It does pass emissions, not with flying colors, but easily, and with very old gas.

The problem started occurring after the pump change, but not immediately after. The pump change happened around 185k. The truck now has 209k. The problems started happening around 200k I guess, it has been several years now and I have not done much with it. Estimates to fix it ranged up to $2300.

I have not taken the truck to a dealer for this problem as I am on a tight budget. The last time I took it to the dealer was in 1999 for the head gasket recall.

I thank you and everyone else here who has replied. You have all spent your time trying to help me and I appreciate it.
 

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My bad water does sink in oil:rolleyes:. Harder to tell if there is coolant in oil than oil in coolant. Just make absolute sure there is nothing in each.

Let talk about having to constantly refill the truck with coolant. This is what you mean by regularly right? How often? When I had a busted radiator I had to drive with 2 jugs of coolant with me. I was refilling every 2 days maybe. Thats a bad leak.

When the coolant level drops far enough,... theres not enough coolant to be pumped into the the heatercore which is your heater. You wont have any heat from it. As you start driving with heat build up and the pump turning faster some coolant makes it way into the heatercore again. Giving you some heat.

First question. How often do you refill.

Second. When you fill up with coolant, do you ave heating problems?

When you start overheating do you notice theres no coolant in your engine?

You have a leak man! I dont think you have a clog. I know radiators can glog up but i dont know about engine. Maybe?!?! i doubt it though.

To rule out a clogin your engine,... if your over heating and you refill with coolant and your engine starts running cool again. No clog. Its just that you have no coolant.

The coolant is leaking out somewhere. Depending on how often you refill will determine the signs. refilling often you will have leaking puddles. If its leaking into your oil you would see it. same for coolant. If its leaking into your cylinders your engine would be burning it. In that case you would see white smoke or something unusual out your tail pipe. These are the tel tale signs. It has to be going somewhere,...

So I think you have a coolant leak and your truck only overheats when coolant is depleted. Find the leak. Get yourself self a leakdown kit and test your head gasket,... but like I said, the coolant has to go somewhere. if not in your oil, coolant, or coming out your tail pipe,... theres a good chance your gasket is fine.

If you have a slow leak and your burning it,... you might not notice anything out your tail pipe but from the impression im getting its not a slow burn.
 
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