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1999 Accord with F20B6 engine losing coolant

dandreye

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Accord 2L MT (CL7)
Hi All,

A few weeks ago (early in August) while driving slowly through a 50mph restricted section of a motorway I noticed coolant temperature arrow leaving normal position and gradually moving up fairly fast as I drove towards the nearest Tesco, almost touching red mark at the end of the scale at the end. The radiator apparently leaked along the upper seam between metal and plastic and accepted almost 2.5L of water when I topped it up in about 30min. I then reached home safely and repaired it using Loctite 5660 silicone sealant instead of the rubber gasket and the seal looked almost perfect upon testing. Had no more issues over the next 1-2 weeks of driving although expansion tank was empty when I checked it soon after fixing the radiator (which I disregarded, attributing it to possibly stuck air somewhere escaping the system).

Much to my surprise (as I did the repair job very carefully, removing lots of oxide and/or rubbish from gasket slot and abrading it to bare aluminium) the same symptoms reoccured yesterday under exactly the same circumstances. The radiator apparently leaked through the repaired seam in several places and accepted about 1.2L of water this time.

Before buying a new radiator I'd like to understand whether the problem likely starts from water leaking through poorly (as it appears) repaired radiator or elsewhere? I don't see any leaks under the car when leaving it in the office parking lot or at home overnight. My worst worry is: are F20B6 engines known to have their cylinder head gaskets occasionally get damaged by the time they reach ~180k miles? (I'd hate to learn that it's not uncommon)

Notes:
- back in spring last year I had what looked like a native water pump replaced with QH QCP3175 along with the timing belt replacement at ~167-168k miles just in case it matters
- also in spring last year I had the problem described happen once (first time ever actually) as the same radiator leaked through the lower seam between metal and plastic, which I repaired using Loctite 5699 silicone sealant and coolant temperature arrow never left its normal position for over a year by now, under any driving conditions.


Many thanks in advance!
 
Do you have any other symptoms to indicate a head gasket? Water in the oil or vice versa perhaps? If you haven't and the car was driving ok then I wouldn't worry. If I were you I'd just bite the bullet and stick a new radiator on it. If you still lose coolant afterwards I'd stick a bottle of k-seal in it.
 
Alans27:

Thanks for your reply. ***uming whitish exhaust fumes when warm and/or a bit of foam or bubbles on the oil cap are some of the symptoms indicating head gasket damage, no I can't see either of those; been regularly topping up engine oil and would likely notice anything different than oil if it were there. I haven't noticed any oil in the coolant either, both when it was still antifreeze and now that it's water although I never inspected them for the presence of oil or anything else. Question is where can it escape so that it goes totally unnoticed... whenever I had any leaks with any of my cars I'd always find some coolant on the asphalt underneath.

Btw is it any worse if I try K-Seal with the current radiator before replacing it? Perhaps it'll seal the radiator too this way, and if not I ***ume I could try K-Seal again after radiator replacement if still required, or it can only be used once?

The car still drives as well as ever. The only thing that seems to be happening lately is as if one or more cylinders don't fire very briefly during acceleration resulting in a slight instant push back, which however is so hardly noticeable and so infrequent that could even be happening only in my imagination ) I attribute it to the spark plugs that have probably done their 20k miles (regular not iridium ones) and so may need replacing.
 
I think you need to a proper repair on your car rather than hack jobs using seals. CHange the raditaor and offending hose pipe, it won't be that expensive to do.

Also no known common fault with the HG on these engines, they are as bulletproof as you can get with cars.
 
exec:

Thank you - I'm just back from a reportedly very experienced local car mechanic, who also advised to swap the radiator and kindly offered to pressure test the system afterwards to find any leaks if still required. I just wanted to be sure that the radiator is the probable cause rather than a consequence of something wrong elsewhere before buying a new radiator as decent quality ones like Valeo aren't cheap. At least now I'm reasonably sure that it's not the head gasket, and everything else wouldn't cost me a fortune to repair.
 
Good to hear its sorted, try and get a Denso radiator if you can find one, better quality and the original system is Denso,
 
exec:

Well, not fully sorted yet but at least doesn't seem to be as bad as it could be ) Are Nissens radiators top quality ones as well? Been watching one of those as well as a Valeo one; have also read something good about BEHR ones, which seem to be aka Hella. Will check Denso ones as well.
 
One more question if I may: is it OK that my engine takes just ~5min to heat up? (meaning that's how long it takes temperature arrow to reach its normal position from cold) I've never watched it before and so have nothing to compare it with now.
 
dandreye said:
One more question if I may: is it OK that my engine takes just ~5min to heat up? (meaning that's how long it takes temperature arrow to reach its normal position from cold) I've never watched it before and so have nothing to compare it with now.
Yes, completely normal. Mine takes the same time, or even less, although it depends on the outside temperature.
 
Oh yeah they heat up ridiculously quick! Be great come the winter :)

In answer to your question, no I wouldn't add a k-seal to the current radiator in the hope of curing it. It sounds like from what you've said that radiator has well and truly had it. It's knackered lol. Best change it. I'd only add a k-seal if it's still using a bit of water once you change the radiator. K-seal is very good stuff, but it can't work miracles and that radiator needs a miracle.

dandreye said:
Alans27:

Thanks for your reply. ***uming whitish exhaust fumes when warm and/or a bit of foam or bubbles on the oil cap are some of the symptoms indicating head gasket damage, no I can't see either of those; been regularly topping up engine oil and would likely notice anything different than oil if it were there. I haven't noticed any oil in the coolant either, both when it was still antifreeze and now that it's water although I never inspected them for the presence of oil or anything else. Question is where can it escape so that it goes totally unnoticed... whenever I had any leaks with any of my cars I'd always find some coolant on the asphalt underneath.

Btw is it any worse if I try K-Seal with the current radiator before replacing it? Perhaps it'll seal the radiator too this way, and if not I ***ume I could try K-Seal again after radiator replacement if still required, or it can only be used once?

The car still drives as well as ever. The only thing that seems to be happening lately is as if one or more cylinders don't fire very briefly during acceleration resulting in a slight instant push back, which however is so hardly noticeable and so infrequent that could even be happening only in my imagination ) I attribute it to the spark plugs that have probably done their 20k miles (regular not iridium ones) and so may need replacing.
 
Alans27:

> It sounds like from what you've said that radiator has well and truly had it. It's knackered lol.... K-seal is very good stuff, but it can't work miracles and that radiator needs a miracle.

Looks like: I should appreciate that it served well for so long. Meanwhile I was wrongly expecting a lot more from my own radiator repair job in general and from Loctite silicone sealants in particular: they apparently can't do miracles either )

Will get back with a hopefully happy end once the radiator is swapped and all leaks rectified, if any.
 
skhell said:
Yes, completely normal. Mine takes the same time, or even less, although it depends on the outside temperature.
My missus is envious of how quickly my accord heats up in winter. Her Vauxhall Mokka takes 15 minutes on a dual carriageway to get to normal temperature!!!
 
Talk about Sod's Law.... On my way home from work yesterday (a few hours after reading the thread and posting the above) I was stuck in roadworks and noticed my temp gauge was at 3/4 instead of the usual rock steady 1/4. Luckily I leave my bluetooth OBD reader so I started up the app on my phone and it was way up at 117°C!!! When on the move again the temp came down to 96° but was back up to over 100 by the time I pulled up on the drive. After leaving it to cool down, I found that I was about 2 litres of water short in the radiator!!!

So I've topped it up and will be watching the level closely and checking for damp spots on the drive - but it got me to work and back fine today. Phew!
 
Swapped leaky rad about a week ago (for Nissens 68117). So far so good although too early to make any conclusions yet as I'm not doing many miles lately.


ChrisC78: you may not see much coolant underneath the car if your rad leaks only under pressure as mine used to. Hope neither of us was unfortunate enough to have cooked any gasket in the cooling system during excessive temperature )
 
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