| Well, it is that time of year where the weather starts destroying my car! Anyway, I spotted a very small coolant leak from the base of my radiator ages ago and just kept an eye on it until this weekend where the leak seems to have grown somewhat. Strange thing is that it leaks slowly when sitting overnight, leaks significantly when started cold but stops leaking when the engine is hot. (explain that one techies!) I do not think there are any hoses in that area (base of radiator behind the fan) so that might mean a fractured radiator. I know some of you have replaced the radiator, so what prices am I looking at here? The car is a '90 at 95K miles so I should start expecting these things I suppose. (1/00) |
| IMHO it must be a hose and somewhere really low, maybe the one at the bottom of the radiator. So, when sitting overnight water comes to the lower part of the circulation and drops slowly. When you start the car water pump comes alive and the pressure increases the leak, but when the engine is hot the material widens (not really the right term) and closes the hole. Try to locate it when starting the car in the morning, it should be easy. (At least I hope so). (1/00) |
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It is a leak .. what happens is that the leak is so small that when the water is hot is it evaporating before it gets close enough to the surface to be visible... I take it that there are brown streaks there from evaporated water? This type of failure is quite common on aluminium/plastic rads with steel crimps = 5 radiator construction .. it is age related .. seems to be the aluminium is stress when the radiatior is made and then starts to age .. and this creates a leak .. could also be the thin bit (stretched by crimp process) and the steel crimp + salt off the road makes a merry little corrosion cell .. it is one of those bits I waxoyll...out of bitter experience ... lost 2 radiators this way ... it also tends to happen in the spring as the salt level drops and the moisture content goes up .. never worked out exactly why but I suspect too much salt inhibits excessive corrosion but just the right amount accelerates it .. or something... end of drivelling... (1/00) |
| The leak on the radiator is probably so small that the water evaporates as it leaks when the radiator is hot - I used to have a mini which did the same, a small puddle collected on a seam on the radiator but it dissapeared as the engine warmed up. Try rad weld or similar, its comes in small bottles and is quite thick and gooey. I think it works like this - It flows harmlessly through the coolant but if it finds a hole it leaks through and eventually plugs the gap, probably similar to that tyre weld stuff. Its not permanent but you'll get quite a bit of extra life out of the Rad. (1/00) |
| The bottom hose. Well worth checking before lashing out for a new radiator. (1/00) |
| And where do you think the bottom hose of the radiator is? You've guessed it, hiding under the cooling fan. ;) If you remove the gravel tray you should be able to see it. (1/00) |
| My Mk I overheated on the motorway on Monday. The dealer diagnosed a blocked radiator and replaced it. Has anyone else had the same problem? Am I right to think it might have something to do with the coolant change in last year's service? I did notice a drop in heater output shortly afterwards. (6/00) |
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Don't want to scare you, but this sounds awfully like an air lock, NOT a blocked radiator, as your "dealer" says. Did they show you the rad that they removed ? Did they make an attempt to flush it first ? Did you tell them to replace the rad ? If you had the coolant changed last year, I can't imagine it's got blocked already, unless they forgot to put anti freeze in it or something daft (which, without the rust inhibiting properties makes it rust like an old Lancia), which lead it to block up. Most rads I've ever been in contact with have flushed out a treat - either with an additive (e.g Holts' Radflush) or reverse flush it with a hosepipe. Additionally, the drop in heater output would suggest a lack of coolant in the system, or possibly a thermostat stuck in the "open" position i.e. cooled water is always passing around the system. This wouldn't lead to overheating though - quite the contrary. My old man used to remove the stat from his Rover in the summer when I was a boy for this very reason ! This sniffs a bit to me. I don't know if they will still have the rad, but I would ask for a second opinion. Sounds like they've put one over on you. (6/00) |
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I do have the old radiator, and I intend to get it checked independently, or perhaps just cut a cross-section through it myself. The dealer's report says the radiator header tank was full, but that there were cold spots in the middle of the radiator, indicating blockage. My worry is that an incorrect coolant mixture was put in last year, resulting in scaling and/or corrosion which blocked the radiator and reduced the heater's effectiveness. Could there be effects in the engine itself as well? The radiator replacement was done under guarantee, so I don't have to pay for it; but I am worried about what caused the problem in the first place, and any further consequences. (6/00) |
| Never seen a radiator block if coolant is changed and there's anti-freeze in the system. Still it's is possible it was blocked. When I changed the coolant on our '92 in came out jolly clean looking! But maybe those who refill with de-ionised water have a point. Keep an eye on that temperature gauge! (6/00) |
| I had the same problem a couple of months back. The car suddenly started to overheat after the 45k service but I don't think they touch the coolant during that service? Mazda replaced it for free and delivered the car back to me - no cost at all........I was so surprised that I even rang them back up as I was sure they would charge me for something. Since the rad change not had any problems at all - but it does take longer for the engine to heat up from cold now. (6/00) |
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The dealer's report says the radiator header tank was full, but that there were cold spots in the middle of the radiator, indicating blockage. Hmmm, it would, but I suppose if the fins on the rad had taken a few dents on its time, then I suppose its feasible that if the fins became bent, it might restrict the flow of water. I really do not know - I'm guessing. For what its worth, I got a look at my rad recently on a picnic (seeing as I was laid out next to it) and was quite shocked at the state of the rad. And my wife hasn't done much motorway mileage at all. Enter Mr Andy Fox and one of his quality Donutz grilles ! Could there be effects in the engine itself as well? Possibly. The block is cast iron, and will rust if the wrong coolant is used. That's why they use a large percentage of anti freeze - to stop rust, rather than being able to keep the water as liquid at -50 degrees! but I am worried about what caused the problem in the first place, and any further consequences. I agree. You need to get to the bottom of it. (6/00) |
| Did they change the thermostat as well?? (6/00) |
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Hum .. add rad flushing agent then remove and back flush rad with water .. replacing rads is just a lazy/cheaper on labour option by garages.. but if it cost you nothing .. just smile as now you have a new rad and the old one was probably a bit fragile. .. and the reason you need anti-freeze is to stop the aluminium corroding and reducing efficiency.. good old cast iron block does not really care. I would question state of; |