Re: Bypassing heater core & removing coolant

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Well, the heater core is now flushed, then blown out with air. The acrid fumes seem to be gone, but the acid test comes when I set fan on ventilate. Since this could result in days of coughing if the problem is still there, I am putting that off until certain deadlines and committments are met this weekend. The problem that led to this was negligence on my part: not checking the oil, having a leak, and running the engine dry. It was replaced with a used, non-rebuilt engine. Thereafter, the valve seals were changed to eliminate black smoke in the exhaust. The only persistent problem is a progressive drop in oil, and the acrid fumes. Someone here suggested head gasket problem and a pin hole leak in the core, which might cause coolant to mist into the passenger compartment due to overpressurization of coolant. I talked to my mechanic about its likelihood, considering the improvement in air quality with the coolant bypassing the core. He is convinced that if there is a core breach, it was not caused by the replacement engine. Any breach would have happened with the old engine burning out, though he admitted that was unlikely too.

What you guys think? He certainly has a point, if the head gasket was good. There is every indication that it is: no cross contamination between oil & coolant, no changing level of coolant, no blue/black smoke, no film on the spark plugs or rusting of threads. On the other hand, there is this steady oil loss, dropping from just above the "high" mark on the dipstick to midway between "high" and "low" marks over the span of 1700km. As well, it is hard to imagine exactly how the core could be ruptured by running the engine dry prior to its replacement.

Thanks for any thoughts on this.

Tercel Owner

P.S. About oil loss, what is acceptable? Is specified in liters/km, or is it specified as how many km's it takes to go from the "high" mark to the "low" mark? How many liters is it from high mark to low mark? None of these seem to be addressed by the owner's manual. Is the acceptable decrease in oil documented somewhere? What about the volume from high mark to low mark? TIA...

Reply to
Tercel Owner
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The heater core leak is unlikely to be caused by your former or current engine unless the heater core was defective or in poor condition and the engine overheated and the pressure at which the radiator cap rfeleases pressure is higher than the weakened condition of the heater core could withstand. If all 3 conditions were present, then it is only a matter of time before the heater core starts leaking. The most likely cause of the heater core leak, if there is one, is just old age and/or lack of maintenance of the cooling system.

The generally accepted rule of thumb for oil loss/consumption is 1 quart per

1,000 miles, or 1 liter per 1,600 km.

The volume of oil from the high mark to the low mark is usually 1 or 2 quarts.

Reply to
Ray O

Ray O wrote: > The heater core leak is unlikely to be caused by your former or current > engine unless the heater core was defective or in poor condition and the > engine overheated and the pressure at which the radiator cap rfeleases > pressure is higher than the weakened condition of the heater core could > withstand. If all 3 conditions were present, then it is only a matter of > time before the heater core starts leaking. The most likely cause of the > heater core leak, if there is one, is just old age and/or lack of > maintenance of the cooling system.

OK. It's just freaky that the problem happened exactly when I got the engine back. So I guess all 3 conditions must have been in effect. I should get the cap pressure checked out, as well as then oil light. So many stars were aligned, leading to the catastrophic failure....

Thanks, Ray. The local Mendes dealer/garage/body-shop says something similar i.e. 2L from High to Low, 1L per 1000-1600km. That means I'm a bit on the high side of typical. Ugh. So be it. I wonder how such a low mileage engine gets such worn rings & valve seals. Let that be a lesson to you boise & gills: don't forget to check yer oil......

Tercel Owner

Reply to
Tercel Owner

I'm not suggesting that your radiator cap is bad, although your mechanic should have a device that checks the pressure that the cap will hold before releasing.

For example, if a cap is designed to hold up to 45 pounds per square inch and and if the cooling system pressure gets above that due to overheating, then it will vent the pressure. When a cap vents, you see the clouds of steam associated with an overheating car. If a part of the cooling system is weak due to corrosion, damage, etc, it might leak at 5 or 10 PSI, much less pressure than it would take a properly working radiator cap to vent.

>
Reply to
Ray O

That means the core was waiting to rupture in the first place. It makes sense that if the engine heats up, the coolant would pressurize. Dang. Thanks for drawing the picture of how it can happen. I won't be left wondering if I was taken.

Tercel Owner

Reply to
Tercel Owner

Greetings Tercel Owner

I first mentioned the heater core leakage lang ago. In my experence I was retaling to you when I worked for an EMS service and we had a van ambulance that we went through two heater cores before it was found the cause was a leaking head gasket.

If you do not change the coolant in your vehicle on a regular schedule you will get and deteriation of the cooling system both in ability to cool and rust or worse.

If the heater core is your problem do this

(1) change it with a quality brand core, no junk yard parts also replace all hoses and clamps (cheep insurance for future problems)

(2) change thermostat and radator cap with the proper ones

(3) have mechanic run vehicle to temperature and have in place a pressure guage snd see if cooling system pressure changes out of normal range before and after reaching operating temperature

You can have a leaking head gasket that does not leak all of the time, temperature related or how about a cracked head/block also.

Sounds like you have agood mechanic that will work woth you, keep him/her

C.

Reply to
C.

You're welcome! Good luck!

Reply to
Ray O

C. wrote: > Greetings Tercel Owner > I first mentioned the heater core leakage lang ago. In my experence I was > retaling to you when I worked for an EMS service and we had a van > ambulance that we went through two heater cores before it was found the > cause was a leaking head gasket. >

He can be pretty good about some things, but I have to be careful. It hasn't always been the case that I could have him (without exasperation) elaborate on the findings & tasks on the work order so that I knew the state of my car. Eventually, he accomodated my need to know what was going on. This seemed to be a good thing to push for, from discussion with a car-savvy friend; one needs to take personal responsibility for the condition of one's car, regardless of the professional services gotten. From what has happened since changing the engine, this seems very true. There have been a spat of things which make me less than comfortable about taking his assessment at face value. For example, the mechanic has always been emphasizing that the engine was good, there were no leaks, and the core was fine (despite my detailing the possibilities learned here and from discussion with friends). This is based on analysis of the exhaust, lack of oil/coolant mixing, and lack of coolant film on the inside of the windshield. Despite his assurances, changing the valve seals /did/ solve the oily black fumes in the exhaust, there was a highly visible leak where the crankshaft enters the transmission, and the air /does/ seem easier to breathe with the coolant bypassing the core. The oil leak wasn't found even after several visits. I would have checked myself earlier, but my ramps are not easily accessible. In the end, I crawled under without ramps, which meant doing a load of laundry afterward, since I was force-fitting myself under the car (had some trouble getting out).

On top of that (no pun intended), his method of tracking oil loss can be somewhat disturbing-- the current mileage and oil level is compared to a data point taken a while back, ignoring the fact that there was a top-off to above the high mark about midway between then and now. This was after the leak was fixed, and there was no paperwork done for it, and hence no data point. This was pointed out, and partially annotated in the current paper work. However, there was also a large discrepancy between his current oil level reading and mine, which was attributed to me not measuring it while it was cold (apparently very inaccurate). I was waiting 5 minutes after the turning off the ignition (owner's manual says wait a few minutes), and found such readings to be very consistent regardless of external temperature, despite his warnings of all the ways it can be wrong. To test his explanation, I made the reading on a cold engine and found a minor discrepancy of 5%. When I brought it in to show him my reading, it turns out that the reason for the discrepancy was that the car was not on flat ground. I would have thought that this was common knowledge for a mechanic. It costed about 1.5 hours that morning resolve (I assume that it has been resolved), and quite a great number of hours of pondering whether this was intentional, and going to get and objective 3rd party opinion on my reading and the accuracy of measuring according to the owner's manual. The pondering itself was well justified, given that the mechanic was always convinced of the engine's fitness, and somewhat reluctant to engage in troubleshooting, and getting more adamant as time progressed, despite the real problems found. The coolant bypassing was a minor item covered by myself.

Having said this, I realize that he has gone out of his way on some troubleshooting under the engine's warranty, such as throwing hot water over the oil, checking the core for damp spots, and blowing out the air ducts. Any big-ish items related to the engine was apparently covered by the business where he got it from e.g. the valve seals.

I guess the bottom line is that his /intent/ is professional, but his assessment needs to be verified. What was that Russian saying?... "Trust, but verify". So his intentions are trustworthy, but his assessment needs critical assessment. This is pretty well what my car-savvy friend was getting at. You alone are responsible for the well-being of your car (which I realize is a less of a black art for those who work in the area), and should be convinced yourself of its condition rather than simply relying on the assurances of your mechanic.

I'm considering changing the heater core as a personal project this summer. I wonder if this is realistic, as I have heard that removing the dash is like microsurgery and neural surgery combined. I have a Haynes manual for 87-94 (they don't have more recent ones), while my Tercel is 97. The "body" section of the 87-94 manual has rather simple looking descriptions of removing pieces of what I consider to be the dash ("instrument cluster bezel", glove compartment, steering column, center trim panel, front & rear console). There is official

97 Tercel repair manual for about $150; from looking at my official 89 repair manual, it looks to be about the same level of detail as Haynes, except that it actually details the screw sizes and types. How advisable is it to go ahead using the 87-94 Haynes manual on my 97 Tercel? "Qslim" suggested becoming a member at
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Has anyone found this to be a moreillustrative source of info on disassembling the dash and/or changingthe heater core? Thanks for the advice on preventative measures to avoid another core breach, I'll follow up on that after changing the core (be it on my own, or asking a mechanic to do so). Too bad, there use to be a do-it-yourself place in town that where the owner can coach you along.

Tercel Owner

P.S. Given the plethora of screws and thingies that have to be pulled out to remove the dash, how do experienced mechanics keep track of them all? For example, I was thinking of taping each screw to the item which it fastens so I know where each one goes. Is this dumb? Smart? Are there better ways?.....

Reply to
Tercel Owner

When you check oil levels, waiting 5 minutes or so after the engine has stopped should be sufficient to let all the oil drain back down to the oil pan. Whether the engine is hot or cold should not make an appreciable difference in the level indicated on the dipstick. To check the oil, make sure the car is on level ground, pull the dipstick out, wipe it clean, and re-insert the dipstick all the way back in as far as it goes before pulling it back out to read the level. Note the mileage and date and then you can get an idea of how much oil loss, if any, there is.

Use a 50-50 mix of anti-freeze and water (distilled water is best), fill the radiator and overflow bottle, start the engine, and let it warm up. Keep an eye on the coolant level in the radiator, topping off as necessary until the engine if fully warmed up. Replace the radiator cap and top off through the overflow bottle.

Cconsider taking an auto shop continuing education course at your local high school or community college. They have facilities and tools to use for your hands-on portion of the course and you'll have the guideance of the instructor in case you get stuck.

Taping a screw next to the hole it came from is probably a smart way to go although I have never done it that way. After taking lots of things apart, you just get a knack for what type of screw goes where. As you remove screws, keep in mind the length, diameter, and type, i.e., sheet metal, self-tapping, washer attached, etc. I just group screws together on the floor mat in an area where I won't bump them, in roughly the order they came out.

Good luck!

Reply to
Ray O

Yes, taking the reading seemed straightforward. When there is such a huge discrepancy reported, and when my readings (which are consistent with time, made according to the manual, and done this way for over 10 years) are marginalized based on measuring it warm...that's when I worry about the objectivity of the assessment. That the apparent source of discrepancy was nonflat ground doesn't alleviate the concern much. Normally, I wouldn'question it, but it has come on the tails of other baffling oversights and constant reassurances.

I think I've already experienced some of that trying to get a better look at recently. Didn't really recognize anything except the interior vent intake, as pointed out by the mechanic. That seatbelt receptacle on the driver side really digs in!

I just looked at the sections of the Haynes manual for emptying out the coolant and accessing the heater core. I think you're right about signing up for a course. Doing it on one's own for the 1st time wouldn't be so bad if said person had a sheltered garage and lived beside an automotive hardware store, but if I don't finish in one day, stuff will be spread out everywhere in the parking lot for this apartment building's. If I need anything from the hardware store, that means 2 hour walk, round trip.

Funny that the coolant system gets flushed with water after emptying. It's so toxic, I wonder why it's OK to have trace amounts in the flush water.

Most of the gas stations sell prediluted coolant, with the right mixture for the prevailing temperature of the season.

For sure. After seeing the manual. I recall taking an automotive course in highschool, a lifetime ago. Not much hands on. Lots of theory and memorization. A bit like trying to read a textbook on one's own. Mostly the engine internals, none of this stuff about electrical, coolant system, timing belt, alternator, etc., except on paper. And when we did have the do-it-yourself place open in town, my experience there seemed to have very little to do with the theory & engine internals I saw in highschool (most nonprofessional maintenance will not be about rebuilding engines). So I'll look for a more hands-on maintenance-oriented course.

I might do that when I get professional at it ;) . For now every crutch helps, so I'll pick up lots of tape. And lots of sticky labels.

Thanks. I think it will come in might handy!

Tercel Owner

Reply to
Tercel Owner

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