Ocenica

We had the Honda Civic EX 2002 overheat about month ago. When I went to fill up the radiator I found this yellow gunk caking the top of the radiator. I didn't know what it was so once the car was back on the road I put radiator cleaner in it and ran it around for a while then washed it all out with new fluids twice.

I check it today and the yellow gunk is back. Not sure what it's coming from. The oil levels are fine, it does have a very slight leak (220k miles on the car). As well there is a code P0401 (Generic) EGR insufficient flow valve.

Could these two issues be related? What causes the yellow gunk?

Notes:
-The oil is not milky and at regular levels.
-The car runs well (no more overheating or vibrating)

Any advice or ideas is appreciated.

Thanks,

Reverb2005

Blown head gasket.

Yellow gunk IS oil in the coolant. Small amount, so you may not notice the oil level dropping.

Doesn't matter, oil IS getting into the rad.

Doesn't matter, it DID overheat and it WILL happen again.

Head-gaskets fail in strange ways and the problem doesn't always replicate itself right away or ever.

EGR valve is probably not connected to the problem, it is probably clogged, common problem. You can try to remove it and clean it with some carb cleaner.

Ocenica

Awesome, this is what I needed to know. It sucks this happened, but at least I now know what I am up against. Now for the next part. I've done basic maintenance on this car and others (oil changes, spark plugs, brakes). How much more difficult will it be to redo this head gasket? Is it worth it for a novice with tools and a Chiltons guide, or should I spend my time finding a mechanic that can repair this and or scrap the vehicle?

Ty for advice

Reverb2005

Well doing the HG job yourself will save you TONS on money on labor, but it really depends on how deep you feel comfortable going.

I wouldn't say a HG job is for a novice, but that doesn't mean you can't do it; you just need to do the research, have the right tools, time and energy for it.

The car would likely be down for at least a weekend if everything goes smoothly, possibly longer.

There is a nice DIY on this site:

https://www.civicforums.com/forums/1...elt-diy-6.html

And lots of others if you Google it. Read through it and see if you think you would be able to tackle it.

Your car year/model is prone to HG failures, that being said, it would likely be a one-time fix. As for if it is "worth" doing or scrapping it, that is a decision you will have to make. HG job costs can vary widely between shops and the cheapest route is usually the worst option, IMO.

Is the car otherwise in good shape? Rust? How's the suspension? Anything else you figure needs to be done?

At least if you fix this one, you won't go out and buy another one and come across the same problem down the road. I always look to fix a problem, rather than just throw the item away, no matter what it is, but that's just me.

Ocenica

Ty for your responses. I am actually looking at the project as a 'learning experience' so I might just take it on. Gonna check the guides and some youtube vids and see what I can mentally calculate out. Time is the biggest issue, and that is why I appreciate your time and responses very much.

Thanks and I'll update soon.

pjb3

Doesn't look like oil in the antifreeze to me. I'm wondering if you have had incompatible antifreezes added to it and they are forming the sludge. If there is sludge it will limit circulation and could cause overheating.

If you do a search there is a procedure written by Ezone that tests for the most common way the head gasket leaks. Yours may be one of the few that fails in another way but if it passes Ezone's test I would do further analysis/tests before assuming it is the head gasket.

Reverb2005

pjb3 is right, you should probably perform some HG tests before you rip it all apart. The problem is, is that you may waste your time finding that it passes all the tests and it could still be the HG!

The yellow stuff... is it slimy, oily, sticky, gooey? What the best description?

Oil in coolant can look different depending on how the car has been running and sitting. Coolant (Water, propylene glycol and some additives) is a polar substance, while oil is a non-polar substance; they do not like to mix! So oil in the coolant may look like oil in water, that is, it would float and form oil bubbles and not mix well. However, the propylene glycol allows for well mixed oil and coolant to make an emulsion, that is, a very highly-mixed substance that still separates into its sub-components.

The yellow-substance in your rad looks like a very good example of this type of emulsion and this is why I (plus the overheating) would come to the HG conclusion.

Still, doing more research and finding an appropriate course of action will ensure you do the right thing.

ezone

The P0401 is usually caused by clogged EGR passages. You can clean those out while the head is off for the head gasket work.

The yellowish gunk?? Weird color IMO.
What color antifreeze was used in it?
Could it be a stop leak or sealer?
If it's oil then it should feel and act like an oil.

If it's yellow coolant that's been boiled hard, that could explain the yellow goop.
I see the radiator kinda looks low too.

On the radiator cap, are the thin rubber gaskets all distorted and swollen? Radiator hose or any of the small coolant hoses mushy? That would indicate presence of oil in the cooling system.


If it's been seriously overheated then the head could be warped, and that could allow pressurized oil to breach the head gasket and enter the coolant area in the block. IF it's oil.
And if the head is truly warped that bad, I'd expect to see (at minimum) the middle two cylinders fail the leakage test I usually do.

Ocenica

Thanks for responses fellas,

Okay so the gunk is sticky. It pretty much disintegrates when you rub it between your fingers into nothing. I have not added a sealer to the radiator nor the the oil. It's synthetic oil and just 50/50 mix antifreeze (Discount Auto Parts kind.) I'll see if I can find those EZONE tests and check that out. The weird thing is, the car runs perfectly fine, stays cool, long distances etc etc no clunkyness at all. For sure though that gunk is telling me something.

Okay ty for the responses again I really do appreciate your time as I diagnose this darn thing.

ezone

Well, THAT'S new.

So it's like some sort of foam or suds?

*scratches head*
Could it be leftover remnants or residue from this?

And is the radiator level really low in the pic?

Testing for extremely slow combustion leakage into the cooling system:
HTH

usajags84

Did you get the car used? How long have you owned it?
The reason why I ask is I worked on cadillac northstar engine in a deville a few years ago that someone used headgasket in a bottle on when I flushed the radiator is looked simular. Granted it was redish from the coolant but the consistency sounds right.

My learning experience from that was was to make friends at a machine shop that engine had more helicoils (gm had a problem with the blocks the heads would work their way loose from the threads collapsing

Since the 7th Gen is prone to head gasket failures I could picture that happening