Honda H23 blown head gasket - 3500S
I got my Rover 623 towed to a garage yesterday after a cursory inspection from an RAC man who was a little surprised that he'd seen a Honda H23 engine with a suspected blown head gasket.

The prognosis at the garage was a blown head gasket. It's a good garage and has searched for a good price on the gasket set from an extortionate £380+vat (non-Rover dealer, usual supplier) to a factored set (same manufacturer) at £90+vat. This has brought the repair down to a more reasonable £500.

Thing is, I'm really puzzled as to how on earth the gasket blew?

It's an automatic to start with, no red line driving since I've had it, not that it's easy to do that with an auto. No cheap oil on my part either; always Mobil 1. Always serviced and looked after. One of those things? Unlucky and that's that?

Any ideas? Just to cure my curiousity really. I was in the process of getting the last of the money together to sell it but I'm wondering about any CAT damage due to burning oil. Would this affect the CAT?
Honda H23 blown head gasket - king arthur
I sometimes mention to people that I've seen Honda engines with blown head gaskets, and they never believe me...

Do you know that it was burning oil, or just assuming? The normal way to tell an HGF is by seeing water in the oil, which probably wouldn't harm the cat - unless you left it too long perhaps. Having said that, a head gasket failure could have many symptoms, one of which could possibly be oil getting into the cylinders.

Has the engine got very hot at any stage? Is the cooling fan working okay? Radiator not clogged? These are the sorts of things that can hurt an engine enough to cause HGF.
Honda H23 blown head gasket - 3500S
I know it was burning oil due to the serious amount of smoke out of the exhaust. It was a lot of white smoke. The water wasn't too bad but only a small puddle in the expansion bottle, it wasn't its usual green colour more a muddy colour. It was definitely more burning oil, the smoke stunk of it.

The exhaust is usually the best place to work out a HGF due to watery soot, no water only lots of soot.

As for temp, the gauge never rose above its usual 3.30pm position, no temp warning light either.

The cooling fan is a good point but it has come on at the right occasions.

It's a mystery to me. The mechanics are puzzled too, I've asked them to do a through check on the engine as it was after a long-ish spell on the motorway before it failed.
Honda H23 blown head gasket - Jonathan {p}
A rule of thumb.

White smoke indicates steam (water).
Blue smoke indicates oil.

Most cars give off white smoke to a certain extent as the cat converts some of the exhaust gases into water vapour.

If the car is using water (from the cooling system) then it can reduce the effectiveness of the cooling, resulting in overheating.

Is there any oil in the expansion tank?

Honda H23 blown head gasket - John S

It's not the cat - it's basic combustion of a hydrocarbon fuel - burn hydrogen and the combustion product is H2O - water.


John S
Honda H23 blown head gasket - Jonathan {p}
Hi John

Thanks for the correction, however, the cat does convert unburnt hydrocarbons to water. So I guess we are both right :-0



Honda H23 blown head gasket - king arthur
Muddy coloured water in the expansion tank indicates rust! Which could mean the waterways in the engine are clogged, which could lead to the head getting hotter than it should (despite a normal temp gauge reading) and leading to HGF. I don't know about the 2.3, but experience with other Honda engines tells that they can be sensitive to the condition of the coolant.
Honda H23 blown head gasket - Mark (RLBS)
this will get moved to Technical Matters later.
Honda H23 blown head gasket - 3500S
Apologies Mark.

Thank you for the insights, my neighbour and fellow classic car owner, did suggest sludge blocking the either the oil or water channels.

So far as rust in the water channels, that would be unlikely, it has a full service history and I never dilute the coolant, pre-mixing a top-up in a old drinks bottle before pouring it into the expansion tank.

My only theory is oil channel blockage causing pressure to build up near the a cylinder bore. As for the steam/smoke. It's got a real oil tinge to it, the block is being skimmed due to the presence of micro-bubbles.
Honda H23 blown head gasket - Aprilia
Honda HGF is not *that* unusual. They used to regularly fail early (60-80k) on the old 2.5 & 2.7 V6's. Honda engines tend to be run hot and have quite small water capacity and narrow coolant passages (for thermal efficiency and quick warm-up).

Antifreeze (from the coolant) may possibly kill the lambda sensor - so it would be wise to check emissions after the job is done.
Honda H23 blown head gasket - M.M
Wonder if it's had regular two yearly coolant changes using quality glycol and perhaps soft water?

Honda H23 blown head gasket - 3500S
Well, the garage has just rang and it's a bit more than a blown gasket.

The cylinder head has cracked, apparently a known fault with the H23 which I admit is news to me.

The bill would be £1200 to get it fixed with a re-con cylinder head. This is something that rings alarm bells already. Bearing in mind that I was going to part-ex it in for a newer car, I probably wouldn't expect to get more than £2000 part-ex.

I'm in a fix now what to do, risk getting it fixed and more nasties coming out costing more money or get shot now and take an £800 hit by not having a car to part-ex in?

Any ideas? I'm scratching my head here what to do.

Honda H23 blown head gasket - Mark (RLBS)
Down the scrappie, get a head, put it on and you might not get 2000, but you'll get more than nothing.

Depending on whether the car is at a main dealer or backstreet chappie, you might find that he'll fit the head for you - although it will be at your own risk.
Honda H23 blown head gasket - 3500S
Exactly, it's too close to call.

I had a chat with a friend in the car business and he did say I'd struggle to get £2000 part-ex, more like £1700 depending on the trade-up for what I was buying. He said I had a better chance going to a main dealer with no part-ex, sizable cash deposit and then throwing them a bone with some finance (about 30% of the amount needed). Something about enough of a sweetener for a finance kickback to keep the salesman happy. I need some finance anyway so that's a fair enough point.

Fair credit to the mechanic at the garage (it's non-dealer, my usual garage and very good too). He can't do anything until Monday in terms of sending the head off for a re-con exchange. So he's given me some breathing space to work it out. He admitted it is a lot of cash and certain risk on it.

I'm dubious myself, I wasn't happy it was 'only' a gasket failure to begin with and I'm following that instinct that this isn't the end of the matter. If I start the ball rolling with getting it fixed then I can imagine something else might crop up pushing it beyond £1200.

The problem with the H23 engine is normally they are bullet-proof and there aren't many scrappers to go for. The garage had a hell of game getting a gasket set for one mainly due to a lack of demand.

I'm off to look at a newer car tomorrow, if I can haggle him down so then I'm up without getting my old motor fixed; I'll scrap it and pay for the three hours labour on it.

I'd never sell it private after that amount of work on it, too much of a conscience I guess.
Honda H23 blown head gasket - bazza
Or... pick up a very cheap banger from the free-ads or auction, to keep you mobile, say £200 max with some MOt & Tax. Put the Rover off the road and look nationally for a second-hand head. Get the Rover fixed by your independant and back on the road. Then part-ex at your leisure, finding the best deal around. Finally sell old banger for what you paid, or throw it away if you can't be bothered!
If you can't source a used head, sell the Rover for spares or scrap. The extra time you've bought yourself with the banger allows you to find the best deal on the next motor without rushing. This way you're less likely to rush into a poor deal.

Honda H23 blown head gasket - Aprilia
I think you will have a problem getting a good head for this engine. If there are any good motors in the breakers' yards then they will want to sell the engine complete - not just remove the good head and sell it alone.

I suggest two options:

1. If the car is in generally good condition (apart from the head problem) then advertise it in the 'salvage' section of your local Autotrader. If the car is clean you might get over £600 for it (a DIYer might buy it and sort the head out themselves).
2. Buy a complete engine and just do a swap - there'll be no expensive gasket set to buy and the labour will not be much more than for the head repair. Try to get a complete engine from a write-off, with 3 months warranty - try E&M or Autotrader.
Honda H23 blown head gasket - 3500S

Bazza, excellent idea. I do have another car but I'm currently stripping out the carbs and need a new float in one. The part is on order so I'm waiting for that and then the six hours of swearing, fiddling and two tubs of vaseline later, back on the road.

So I went out and got....... another Rover P6. £500 for a 44,000miles 2000TC. 6 months MOT, tax emempt, no rust, the paint job is not great, the interior is shot but excellent mechanicals, brakes, etc. It'll cause a stir at any dealership but hey, what an entrance. ;) I'll get my £500 back when I sell it as it'll be great for spares, bonnet and boot are alloy and unmolested and the engine is as strong as an ox. £25 to insure for the month which should be plenty of time.

Big smiles on the way back home, I've never driven a 2000TC but it's quite nippy.

On my current car, I'm settling up on the three hours labour I owe the garage and I'll take 500 notes for it if there's anyone there that wants it. If not, I'll ask if it'll be alright to park it up for a while and go the salvage route. Might even find a breaker that will take it. The Rover alloys alone are worth £300.


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