Yellow dust in coolant and yellow flakes under oil cap (8 Viewers)

[jeanbono]

Hi all,

1 - Just checked my coolant overflow reservoir and the coolant in there (as well as the tip of the hose) shows this yellow “dust”. The radiator is made out of copper with the same colour, could it be corrosion? I know the previous owners changed the radiator, I’m thinking maybe there was a coolant leak at some point and they put an additive in it, but pretty sure this yellow stuff was not there a few weeks ago when I checked. No knocking sounds etc.

2 - I don’t know if this is related but I also found some yellow debris under my oil cap (see picture). I’m going to go back to check to see if it’s metal, have you seen this before? The oil dipstick shows a very clean looking oil, free of these flakes, is that a sign I shouldn’t worry about it? Haven’t planned to do an oil change/cut oil filter open to see bottom as I did one recently, but should I?

Thanks for your help

 

[ppc]

Hi all,

1 - Just checked my coolant overflow reservoir and the coolant in there (as well as the tip of the hose) shows this yellow “powder”. The radiator is made out of copper with the same colour, could it be corrosion? I know the previous owners changed the radiator, I’m thinking maybe there was a coolant leak at some point and they put an additive in it, but pretty sure this yellow stuff was not there a few weeks ago when I checked. No knocking sounds etc.

2 - I don’t know if this is related but I also found some yellow debris under my oil cap (see picture). I’m going to go back to check to see if it’s metal, have you seen this before? The oil dipstick shows a very clean looking oil, free of debris, is that a sign I shouldn’t worry about it? Haven’t planned to do an oil change/cut oil filter open to see bottom as I did one recently, but should I?

Thanks for your help

View attachment 3919114

Can you post another picture of the oil fill from a different angle? What shows in the current photo, bottom left, is difficult to decipher. I don't see the drain to the block where I expected it to be.

 

[jeanbono]

I just went back to the truck for extra pictures.

1-So these yellow “flakes” where all under the filler cap, I took one out and I have no idea what it is, yellow on one side, white on the other, looks/feels more like flaked paint than metal haha. Not sure that’s anything to monitor but I like to check everything. (extra pics below)

Edit: Just cut one strip in half and it stretched, looks like silicon almost. Anyway might have been introduced accidentally I reckon…will see if it comes back after I wiped it.

2-The coolant situation. Way more yellow “dust” in overflow tank than under radiator cap, wondering if that could come from the copper on the picture. (will attach pics in separate post)

 

[jeanbono]

And here are the yellow flakes/dust in coolant

 

[Kernal]

The "additive" the PO dumped in was likely a sealer of some sort ie: head gasket and block sealer, usually containing a sodium silicate compound which hardens from the heat of the engine forming a (brittle) glass-like coating on everything in the cooling system. You could remove the upper coolant hose at the radiator and look at the inner surface, take a photo, and post it up. If it's coated in a brittle crust it's possible someone used a sodium silicate-type sealer in the past.

There are some cooling system/radiator sealers that do not contain sodium silicate ie: meant for radiators and not to seal a block or head gasket.

If some of the particles are rubbery then it's likely from old silicone type sealant (ie: used to seal the oil pans, timing chain cover, etc).

If the same (hard) particles are in the coolant and oil that's a bit worrisome ie: did the sealer (dumped into the coolant) get into the oil via a leaking head gasket or crack in the head or block??

You could collect a sample of used engine oil and send it out to a Lab for an Engine Oil Analysis, that might give you some information about the condition of the engine (wear metals) and if the head gasket is leaking (coolant into the oil), but probably won't tell you exactly what the sealer is/was (if it was added).

You could try flushing the cooling system and changing the oil and oil filter (maybe more than once) to see if it clears up??

 

[jeanbono]

The "additive" the PO dumped in was likely a sealer of some sort ie: head gasket and block sealer, usually containing a sodium silicate compound which hardens from the heat of the engine forming a (brittle) glass-like coating on everything in the cooling system. You could remove the upper coolant hose at the radiator and look at the inner surface, take a photo, and post it up. If it's coated in a brittle crust it's possible someone used a sodium silicate-type sealer in the past.

There are some cooling system/radiator sealers that do not contain sodium silicate ie: meant for radiators and not to seal a block or head gasket.

If some of the particles are rubbery then it's likely from old silicone type sealant (ie: use to seal the oil pans).

If the same (hard) particles are in the coolant and oil that's a bit worrisome ie: did the sealer (dumped into the coolant) get into the oil via a leaking head gasket or crack in the head or block??

You could collect a sample of used engine oil and send it out for an Engine Oil Analysis, that might give you some information about the condition of the engine (wear metals) and if the head gasket is leaking (coolant into the oil), but probably won't tell you exactly what the sealer is/was (if it was added).

You could try flushing the cooling system and changing the oil and oil filter (maybe more than once) to see if it clears up??

Thanks for the precious info!
I don’t think these particles in coolant and oil are the same. In coolant really looks like powder, under oil cap looks like tiny bits of silicon. I forgot to mention I had valve cover and rear main seal done so maybe some slight contamination.

I’ll probably do an oil change and a coolant flush this weekend (and inspect hose) and go from there.

 

[Kernal]

Shouldn't be much silicone used for a valve cover gasket replacement (just a touch for the half-moons) and none for the rear crank, unless
they also resealed the upper oil pan rear arch (and the rest of the upper pan, and lower pans??)

 

[jeanbono]

Shouldn't be much silicone used for a valve cover gasket replacement (just a touch for the half-moons) and none for the rear crank, unless
they also resealed the upper oil pan rear arch (and the rest of the upper pan, and lower pans??)

They have also re sealed the retainer arch to the oil pan, that’s about it, they used silicone for that one, could be the reason

 

[jeanbono]

found some fresh coolant on sway bar and around tranny. Can’t find trace anywhere else. Seems like only a few drops and nothing hit the floor but keen to monitor it. Compression test is the answer to start with?

 

[Kernal]

Look closely using a bright flashlight then take photos with flash at the firewall area behind the engine and to either side of the rear of the engine
also the rear heater pipes and hoses, they run along the firewall and down the right side of the transmission tunnel then under the vehicle (under right floor)

Start from the top, there are multiple short hose sections and pipes for the front and rear heaters, heat control valve, etc.

Using a mechanics mirror or better a fiber-optic camera (there are cheap versions you can attach to your phone) look behind
the valve cover/head ie: between the firewall and the backside of the engine above where the engine and transmission come together.

There is a dye you can add to the coolant, run the engine, then shine a UV light looking for anything that glows.

AutoPro Antifreeze and Coolant Leak Detector UV Dye 1oz

Shop for AutoPro Antifreeze and Coolant Leak Detector UV Dye 1oz with confidence at AutoZone.com. Parts are just part of what we do. Get yours online today and pick up in store.

www.autozone.com

If you still can't find the leak you can buy a coolant pressure tester kit:

Radiator Pressure Tester Kit

Amazing deals on this Radiator Pressure Tester Kit at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[jeanbono]

Great thanks so much for that! Will do this week. Just drove 400km and overflow tanked hasn’t moved but definitely smells a little like coolant when I drive , probably drops falling onto the hot engine. Talking about that firewall, when I brought truck to mechanic for a major RMS repair, I think they pressured washed from the bottom and really damaged my firewall.

Any issue leaving it like this? Any better solution than aluminium tape to fix that mess? It’s also damaged further down.

 

[Kernal]

Can you post up a photo or two of the entire engine bay?

Yeah, the original fiberglass mat-type insulation is very fragile, pressure washing for sure will damage/destroy it.

IMO/IME there's not a lot you can do other than trying some heat resistant (or heat reflective) tape to clean up the appearance
but nothing much wants to stick very well to the dirty loose fiberglass. Maybe cut some of the loose bits away then start one end or one side of the tape on clean metal then run it down onto or along the insulation??

There are products that could be used to completely replace the original firewall insulation but you likely would have to start removing multiple parts to get large sections installed.

 

[jeanbono]

Thanks mate really appreciate all the inputs and will post a pic of the engine bay.

Yeah they definitely pressure washed from the top which is annoying considering how fragile everything in these old trucks is .. that’s what you get for going to a mechanic who works on modern cars 99% of the time I guess next time definitely hitting the country to get something I can’t do myself fixed.

At least they fixed the RMS leak truck doesn’t drip on the floor anymore which I really did not think was possible.

 

[BILT4ME]

Thanks mate really appreciate all the inputs and will post a pic of the engine bay.

Yeah they definitely pressure washed from the top which is annoying considering how fragile everything in these old trucks is .. that’s what you get for going to a mechanic who works on modern cars 99% of the time I guess next time definitely hitting the country to get something I can’t do myself fixed.

At least they fixed the RMS leak truck doesn’t drip on the floor anymore which I really did not think was possible.

As far as the coolant leak, it's very possible that is from the O-Rings on the Thermostat bypass pipe on the RF corner of the engine just above the thermostat. Those O-Rings get hard and start leaking but is hard to find because the coolant drops cook off while driving. You can smell coolant, but can't find it. It took me 18 months to find it on mine.

You'll need to get (3) O-Rings and the nipple that slides into the thermostat housing. Plan on cleaning up the corrosion and silicates that have built up ion there. I used red scotchbrite pads to clean out all the areas needed. Lubricate the O-Rings with fresh coolant when going back together. Yes, changing this will cause a coolant change out. if you have any other coolant hoses that are inquestion, do them all at once, particularly the PHH and the throttle body coolant hose from under the head to the TB.

 

[jeanbono]

I have found (one of) the culprit(s)! It’s that hose at the rear near the firewall. That’s not the PHH, is it? Just trying to get its name to see how to tackle it.

 

[jeanbono]

As far as the coolant leak, it's very possible that is from the O-Rings on the Thermostat bypass pipe on the RF corner of the engine just above the thermostat. Those O-Rings get hard and start leaking but is hard to find because the coolant drops cook off while driving. You can smell coolant, but can't find it. It took me 18 months to find it on mine.

You'll need to get (3) O-Rings and the nipple that slides into the thermostat housing. Plan on cleaning up the corrosion and silicates that have built up ion there. I used red scotchbrite pads to clean out all the areas needed. Lubricate the O-Rings with fresh coolant when going back together. Yes, changing this will cause a coolant change out. if you have any other coolant hoses that are inquestion, do them all at once, particularly the PHH and the throttle body coolant hose from under the head to the TB.

great insight, might check this too and do all at once. I think my thermostat is pretty old too.

 

[BILT4ME]

I have found the culprit! It’s that hose at the rear near the firewall. That’s not the PHH, is it? Just trying to get its name to see how to tackle it.

View attachment 3928359

View attachment 3928360

Yes, that is the PHH.

Do a search on here and read about it.
There are multiple ways to fix it. Depends on your level of commitment to Sparkle Motion.

Choose what fits your skill level and OCD.

 

[jeanbono]

Damn! Wonder how long I can live it like this as I won’t be able to work on the truck this month. Coolant level does not move, wonder how long it’s been like that.

 

[BILT4ME]

Damn! Wonder how long I can live it like this as I won’t be able to work on the truck this month. Coolant level does not move, wonder how long it’s been like that.

The PHH can be finicky. Keep an eye on the coolant and keep it topped off.

The PHH is a problem because it rots from the inside and it may suddenly blow out, causing you to be stranded.

Some people claim to fix in two hours, some in six hours, depending on choices. It is always better to do it on your terms in a driveway rather than the side of the road in the mud.

 

[jeanbono]

Ok, I’ll try to see if it’s not just a matter of tightening the clamp first haha. Thanks