Any tips to clean the valves?

Hi, I’ve got a GTO

Has anyone got any tips on cleaning all the gunk out? Opened it up and it’s crusty to say the least…

Looks like something I’d cook and forget about in the oven.

I would see if there is anything that can be vacuumed out without agitation… then just run better quality high detergent oil and do earlier oil changes. Seafoam if you want, etc… I wouldn’t go and try to wipe/get all that out because if anything dislodges and get’s stuck in a return line; you’re in for worse trouble.

Looks like you recently finished building the car… so unless you want to do a rebuild, future maintenance may slowly clear it up.


Removing the heads is the only practical solution for good cleaning and rebuild that is if you want to regain its original power and performance. Once the heads have been removed you will perhaps embark and a through cleaning and restoration job which can take months if not years, however, in the end, you will not regret it.

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I’m absolutely with bluetahoe on this one. Anything other than head removal and cleaning would be suicide. If any of that crap breaks off and gets a stuck in a oil way, the engine will be destroyed. You also have to consider what caused all that burnt oil. I’m guessing that you have pitted valves and damaged valve seals which has allowed hot gasses to enter the heads. That’s only a guess but either way, you need to remove the heads and clean them properly. Good luck.


The car runs perfect at the moment but it did look neglected when I first got it. Could it be caused from a lack of oil changes and regular services. Don’t want to have to take it apart yet if alternatively I could clean it out with an engine cleaner and see how that turns out…

For now I’m just going to pretend I didn’t see anything haha, spent too long and too much already. I want to get as much life out of the car as I can, so there will be a rebuild in the coming year or two, So will tackle it then.

Thank you for the help


Good call. Meantime SeaFoam has worked really well for me. It safely dissolves the crusted on carbon on my VR4. Super easy to use, I use it before every other oil change. There are some good videos on how to SeaFoam your car, if you haven’t done it before. It goes in the gas tank, intake manifold and crankcase. Pretty cool stuff.


I have been looking into it & will try it.
Ill be doing an oil change this weekend & ive been recommended some detergent stuff that you run for 15mins before the oil change… is that sort of stuff any good or is it too good to be true (if you know)

…as i knowingly step into the path of a tornado…
Ian: i know this will sound like the AntiChrist in the face of such well-spoken, and conforming advice.

However, I do not think that crud will FLAKE in chunks as has been warned. It will dissolve in layers, just like it accumulated over the years.
And since you are planning on a rebuild, and that goop is bothersome, try this:


  • 12Qs/Liters of the cheapest oil you can find
  • 10qts of your favorite synthetic oil
  • 2 cheap oil filters
  • 2 of your favorite quality filters

Now do this:

  1. Pour one qt of diesel into the existing oil in the crankcase. (Dont bother with Seafoam – that is just an expensive package of gobble-dee-gook that has been hyped up using the pseudo science devised by advertisers who selectively pick out facts and spin them like snake charmers.) (NOTE: I do use Seafoam, but not for engine flushing)
  2. start and let it idle ONLY, without revving or driving, for 15 minutes.
  3. shut it down and let it cool overnight.
  4. next morning, again start without revving or driving; again let it idle till hot.
  5. shut it down and dump the oil and filter.
  6. put in fresh cheap oil and cheap filter
  7. repeat steps 1-6 of this diesel flush procedure.
  8. do this process 2 more times (or to your satisfaction based on the color of the flushed oil)
  9. change the flush and filter and put in your quality synthetic oil and filter
  10. drive a few hundred miles (say 200-300) and do a final change of quality oil and filter.


For sure, give a follow up. Even pull the valve cover and check the crud-level.

This procedure is not an experiment, but is used by mechanics all over. I’m sure some daily-grind mechanics (not the over rated snobs in the high end garages who quibble over titanium lug nuts) will chime in to corroborate this…or add some practical extras of their own.


NO, not 1 GAL in the oil sump – ONE QUART. and 10-15 minutes at the most and IDLE only. Restart the next day after the diesel does its work – and again, idle only long enough to get engine hot. Then drain.
That amount of time will NOT ruin the engine! Again, theoretical science becomes pseudo science when there is an attempt to equate theory with reality.

I realize it was a long post and most people are just skimming the article and getting sparked by scattered words, so I guess I will have to invest time responding to the inevitable wild fires that get started due to the seemingly extreme idea, huh.

The bottom line is to get the car going! Not another museum piece, right?


This process makes sense. The formation of H2SO4 is very unlikely and if it does will be in extremely low concentrations. Why? Well modern Diesel fuel is heavily ‘sweetened’ this is the industrial name for sulphur removal- hence why in the UK you see low sulphur at the pump. The other reason is both industrial methods for H2SO4 contact and wet process require a Vanadium catalyst so in an internal combustion engine the activation energy for H2SO4 formation is unobtainable. This I do know as I hold a PhD in physical chemistry :joy:


I’m not agreeing or disagreeing with any individual just pointing out the scientific explanation. What I will say is if you go too shops in the UK for an oil change they regularly try and sell an engine cleaner additive which they put in your existing oil and run the engine up to temperature and then do the oil change. Personally I’ve never needed it as 1. I change oil myself 2. Do it regularly.

However car manufacturers never put this type of method in their manuals. It’s like the timing belt change you can use 17mm spanner’s to hold the cams as per manual but much easier with cam lockers.

Ultimately it is up to the owner of the car to decide- it’s your car, money and responsibility.

Good luck :+1:


The facts are that quite often methods are found which turn out to be much better than manufacturers recommendations. What should be done here,for safety, imho is a comparison of sulphur content multiplied by the amount of time the diesel fuel is in the crankcase. The diesel fuel is only a small proportion of the engine oil and is only in for 15mins. Maybe someone could try it out on an old engine about to be scrapped (on any old car) and check the results ? When I get around to restoring my cars I might just give this a go and post the results but I’ve got a long list of jobs before that gets done.

I’ve just read that in Europe the sulphur content in diesel fuel can’t be higher than 10mg per kg so if my maths is correct that’s 0.001 % So how much sulphur in engine oil ?

an extract from a site
A more permanent solution arrived in USLD (Ultra Low Sulphur Diesel), which contained dramatically lower levels of sulphur than common diesels at the time – a maximum of 10 milligrams for every kilogram. This minimised the need for detergent additives to reduce engine wear, and also addressed the issues of sulphuric acid concentrations in exhaust emissions."

I wouldn’t surprise me if there was more sulphur in engine oil than diesel fuel. I might look it up ? imho opinion the only issue might be the potential clogging of oilways and not the production of more suphuric acid than usual.

Exactly. However, this process has been used probably millions of times in mechanics’ shops…millions. It has had “trial by fire” over decades.
I have used this for decades on old engines with unknown past histories that have looked like the OP has pictured.

Secondly, in response to the question of doubters…no garage ever guarantees that any car leaving their care will be wthout a problem the minute after it leaves!
How many times have you heard from customers that their car did not have a certain problem that seemed to arise in direct connection with their visit to that garage. The connection between point of care and new problem can RARELY be factually established – it can only be hypothesized, like the COVID controversies (to whit, where “evidence” continually arises contradicting the previous “evidence”, on and on and on).

I will echo what others have said to the OP: it’s your car so do as you wish. You asked for advice, and you have really heard from many sides of the issue, which is a good thing, right?


Excellent … you can’t beat experience.

Here’s a chart of sulphur content of various oils/fuels. So diesel fuel has less sulphur content than engine oils and lubricating oils and the same as gasoline :grinning:

In conclusion, adding diesel fuel to engine oil actually reduces the sulphur content overall. imho

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Thank you everyone for the feedback on this, lots of info I was unable to find elsewhere.
Going to try a small engine flush this weekend & oil changes every few hundred miles & see if that clears anything up.

Ill have a further look into the diesel flush & might be something I do before a rebuild to see how it turns out.

Ill keep everyone posted with results as they come thru with the regular oil changes etc, but will be something over the next year or so.

Again, thank you

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Well actually the post did not break any forum rules and was actually stating facts. The reason I deleted it was because I’d already proven you wrong on your fears of increased sulphuric acid production and the post would not really add much to this particular thread and you’d probably come back with a childish response. Xerxes has already stated he has used the process hundreds of times and I have shown that levels of sulphur in diesel fuel are actually lower than engine oil yet you seem to be unable to acknowledge those points ? Don’t bother replying to this post and I certainly won’t be responding to yours.

If anyone wants to ignore my posts etc or anyone elses. Go into your account/preferences and click the “users” category. Type in the search box the user you want to ignore,select the name you want and click the save changes button. Result. It is a testament to Joe’s admin and the really helpful and informative posters on this forum that I have only had to block one poster …ever.

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LOL who mentioned using it for long periods of time ? err not one person. and secondly since engine oil contains MORE sulphur than diesel fuel ,if you’d bothered to check my link, then that blows your theory out of the water. You are a complete waste of my time. Back in the ignore bin with you.

I’ll leave you with this link which you conveniently seem to have ignored Sulphur content