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Engine Overheating Followup

If a properly operating cooling system does not build enough pressure to make it leak, why would want to make it leak?

I've heard this reasoning for pressure testing a cooling system many times and the logic behind it is a lot like doing a cardio-vascualar stress test at a doctor's office - if you're going to have a problem it's better to have it happen where help is available. I agree with this logic to a certain extent, but pressure testing an 18 year old system is like doing a stress test on a 95 year old person - the likelihood that you'll pass is pretty slim. If the customer is willing to spend money to replace hoses, radiator, etc. if the test fails, then I see no problem but the repairs may cost more than the car is worth.

If you are chasing a leak, using dye and black light is probably a lot kinder to the sysetem.

You can check a radiator cap to see how much pressure it will hold before venting. If it is letting air in or not holding pressure, the system will tend to run hot.

I guess I was a little unclear. I meant that a pressure test on an 18 year old car may cause more problems than the customer is willing to pay for.

I agree 100% that the effectiveness of a pressure tester, like all tools is up to the person using it. It sounds like you are a technician and if so, I suspect that you can tell from a visual inspection whether the hoses and radiator are in good shape or not. Hopefully, a doctor is not going to make a 95 year old patient with chest pains and difficulty breathing hop on the tread mill to see what's going on.

Reply to
Ray O
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interesting following this, how does the black dye work?? do you need to flush it after?

Reply to
gp

I just don't see your logic in all this. A 95 year old dies from a stress test, that's a loss of human life. That a far cry from having a raiator hose burst during a pressure test. I have never run across a customer that couldn't afford to replace bad radiator hoses no matter how old the car was. Are you saying it would be better to let the customer drive off with weak cooling system parts that would fail while driving ? Now he drives off and the hose bursts. Now he still has to pay for the hose but add in the cost of a tow and the possiblity of engine damage due to coolant loss. Preventitive maintenance means that you find and fix a potential problem BEFORE it becomes a problem. It does not mean you wait for it to break completly.

But it still does nothing for locating a leak.

This may be a possibility. It's been my experiance that when a customer brings their car into the shop they are already prepared to spend money. They brought their car in because they are having problems and want it fixed.

Reply to
Mike

Actually, the dye is not black, however, it is visible under black light. There are various dyes available, depending on what kind of leak you are looking for. There are dyes for coolant, engine oil, ATF, etc. Add the dye, drive the vehicle for a while, and then shine the black light and look for the fresh trail.

It was factory specified equipment for AMC dealers, I think GM dealers also had a similar kit.

Reply to
Ray O

From what I've seen, it is not the hose that bursts during a pressure test, because an experienced technician can usually tell visually if the hose needs replacement and would recommend a hose replacement.

Older Toyotas used to have problems with the crimp betwen the core and upper and and lower tanks. For some reason, they would last a long time without any problem but when someone did a pressure test, the crimps would fail.

Our experiences are probably a liittle different. 100% of the cars I looked at were Toyotas, and I looked at them becuase A) the dealer was having trouble fixing it or wasn't sure if it needed fixing or not; B) it didn't need fixing but I had to meet with the customer and explain why it didn't need fixing: or C) it was out of warranty and the customer wanted Toyota to pay for it anyway. The people in category (C) either couldn't or wouldn't pay so I keep the age and value of the vehicle in mind when making recocmmendations or authorizing out of warranty repairs.

The OP keeps snipping out his original posts so I don't remember all the symptoms and what has been suggested or checked on the cooling system, but I'm beginning to think there is a head gasket problem, and a pressure test won't confirm a head gasket problem.

This isn't the first time that I might be wrong, but I don't think the OP wants to spend $500 on hoses and a radiator and then find out that he has to spend another $1,000+ on a head gasket on an 18 year old vehicle that is barely worth the cost of the repairs.

Ray O (correct punctuation to reply)

Reply to
Ray O

Ever hear of trimming a post?

Are all Mikes morons?

Reply to
dizzy

No. Are all dizzys dickheads ??? Or are you just a wantabe net cop ???

Reply to
Mike

lots of smoke.

I replaced the coolant last night as per the instructions given and ran it, thought I would go for a drive and as I pulled out, it was blowing a lot of white smoke (note that this started with the engine getting almost to red because it had lost at leat 4 litres of coolant which I added plus 1 litre approx for the overflow) so this was the first time I restarted it. Not sure if it was blowing off steam or it points to a head gasket problem. Anyway, went for a drive and smoke went away, ran it on the highway for about 4 km and it ran good a strong but it idled rough. This morning started it again, still some good amount of smoke and rough idle. Tomorrow I take it to a shop. Looking for opinions: does it sound like a head gasket or is it blowing off some smoke at this point?

Reply to
gp

Check the fluid again!

If it is still full, no issues. If it is low, then I would pull the spark plugs for a look see. If you find one or two plugs really clean and the rest dirty, you have likely found the head gasket leak.

You can also run it with the rad cap off and watch for smoke. Lots of times smoke will come out the rad or you could pinch the overflow line closed and carefully hold your hand over the rad opening for a few seconds to feel for puffs. You can sometimes feel the compression going into the rad this way.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Reply to
Mike Romain

After the 10 minute run on the highway, it was running rough, looking at the overflow, it is a bit higher than when I filled it up to the cold mark but no signs of oil from what I could tell. What would explain the rough idling at this point? --needs some time to recover from the overheat?

I will pull the plugs tonight and try your other tips to feel for puffs.

Reply to
gp

Once it cools check the radiator fluid level. If it is low then the head gasket is suspect for sure.

The rough running could be a failed plug or wire or even some crud in the distributor cap. To check the wires, I use a spary mist of water on them in the dark with the engine running. If they have heat failed, you will get quite the light show.

A head gasket isn't that hard to change on that engine if I remember right.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Reply to
Mike Romain

oops, should be 'spray mist' of water...

Mike

Mike Roma>

Reply to
Mike Romain

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