deposit in radiator hose

Submitted: Tuesday, May 17, 2005 at 14:29
ThreadID: 23063 Views:2667 Replies:6 FollowUps:9
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Hi there,

I was chacking the radiator hose on our HJ61 and when I pressed it, I felt like something crumbled in it-I am assuming there was a deposit in the hose that I broke and it ended up in the radiator.I asked at a car radiator place and was told to just change the hose. Because we are planning a big trip, I think it would be good to flush the radiator and engine, just in case. HOwever, I wonder if it is necessary to chemically clean the radiator, as well (assuming that if there is deposit in the hose, there is also deposit in the radiator). The cooling system seems to be working well, though-had a long trip to Sturt NP a month ago and in the temperatures in mid-30-ies, the engine temperature was just as it should be (1/3 of the temperature scale).Would anyone have a similar experience and advice on this?


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Reply By: Drew - Karratha - Tuesday, May 17, 2005 at 14:39

Tuesday, May 17, 2005 at 14:39
I might be wrong here, but I think the cracking would just be the reinforcing inside the rubber on the hose. I dont think there would have been anything that you dislodged into the engine or radiatior. With the constant hot coolant flowing through the hose and the lack of anywhere for anything to lodge in the hose I would be very surprised if there were any deposits in it.
AnswerID: 111625

Reply By: Footloose - Tuesday, May 17, 2005 at 14:41

Tuesday, May 17, 2005 at 14:41
If your cooling system has a failure you're stuffed. Get the entire system cleaned out and checked by a radiator specialist, well worth the money. Whats the cost of peace of mind against a new motor, tow to town etc
AnswerID: 111626

Reply By: Scubaroo - Tuesday, May 17, 2005 at 15:20

Tuesday, May 17, 2005 at 15:20
Have you pulled the hose off to look inside to see if there's any residual deposit? Surely if there was any deposit in the hose, a chunk couldn't "crack" loose without leaving some signs that it was there in the first place. Was probably just the hose itself you heard, but a visual inspection would confirm any problem.
AnswerID: 111633

Reply By: Member - Roachie (SA) - Tuesday, May 17, 2005 at 15:22

Tuesday, May 17, 2005 at 15:22
At the very least I'd be buying new top and bottom radiator hoses and fitting them myself. Once you've got the old hoses off, have a good look at it/them and maybe evn cut one right open to see what made the cracking sound......could be like the other respondent said above....just the re-inforcing.

On the subject of your temp gauge staying steady even on a hot recent findings have proved something I have long thought to be true; YOU CAN'T 'TRUST' FACTORY GAUGES. My Patrol's temp gauge was going up on occasions and i wanted to know what the 'actual' temperature was and whether I should be worried about it.

So I've fitted a VDO gauge. The sender/pick-up unit is mounted into a piece of stainless steel pipe I had made up; I cut a piece out of the top radiator hose and inserted the piece of pipe in the hose. The results were quite amazing. From cold start up, my Nissan gauge gets to it's usual position (just below half way) and the VDO gauge is reading around 75deg. When I'm driving, the VDO gauge can go as high as 105deg and the Nissan gauge will stay on 'normal' right through that 30 degree spectrum. Once the VDO gauge goes to about 110deg, then the Nissan gauge quickly starts to move up to just over half way. I am led to believe these sorts of temps (ie: up to 110 deg) still aren't anything to be concerned about. However, the thing that concerns me is that there are MANY Nissan and Toyota owners who have vehicles which have temp gauges that never move off normal. However, i reckon the real story (if they cared to check it and know for sure) would show the actual temp varies considerably. The factory gauges are simply designed to show when something starts to go horribly wrong.
AnswerID: 111634

Follow Up By: Member - Captain (WA) - Tuesday, May 17, 2005 at 16:24

Tuesday, May 17, 2005 at 16:24
Hi Roachie,

Just reading how you mounted you VDO temp guage. Just a few questions for you if you don't mind. Is the temp sensor point you used whats coming out of the radiator ie. after being cooled OR is it whats coming out of the engine block ie. actual engine coolant temp, not radiator coolant temp? If I am reading your description right, I think you are measuring the cooled temperature, not the engine block coolant temp.

If you are measuring cooled coolant temp, do you now have the possibility of overheating the engine coolant but as you now have a much better radiator, it may not show up on the cooled coolant side?

Also, my understanding is that Nissan temp guage measures engine block temp, not radiatior temp. Its "normal" range is roughly around the 100-105, but once you start to get hotter, it quickly moves towards the red. Its an expanded scale, just like the ones you get for an ampmeter. hence why when below ~100C it does not appear to move much.

I want to make sure my GU guage is OK. My main concern is that if I start to get hot, say >110C, then my guage starts to show it. From your description, this seems to be the case. Perhaps the factory guage is OK to warn of too hot, just doesn't show temp changes much below ~100C?

I missed the EO threads about the installation on the VDO temp into your GU. Didn't think you could possibly fit anything else in haha. I have been away in Europe for the last month, only got back last weekend and too many threads to read them all.


FollowupID: 368005

Follow Up By: Member - Roachie (SA) - Tuesday, May 17, 2005 at 17:01

Tuesday, May 17, 2005 at 17:01
Welcome back Captain!!
Your question brings me back to a "discussion" (read: "argument") I had with another well-known forumite who shall remain nameless even now. This was the subject of a Post I put up a few weeks ago (sorry I didn't keep a record of the number). My good mate who is almost as old as me, has believed for his entire adult life, that coolant flows from the motor, into the bottom of the radiator via the bottom hose, is pushed/sucked up through to the top of the radiator and the cooled coolant then goes via the top hose back into the motor.

My life-long beliefs have been the total opposite. Lets not even get into cross flow radiators, although even those have a top and bottom radiator hose, so my opinion would be that the hot coolant goes in the top and comes out at the bottom, nicely cooled, ready to be sucked back up into the motor by the water pump's action, via the bottom hose. In fact, some kind soul posted a link to a web site which showed that this was indeed the way that coolant circulates.

Therefore, the coolant that is going through the top radiator hose is the hottest it's ever gunna be, cos it's just come out of the donk and is about to enter into the cooling chamber (ie: radiator). So, my VDO sender unit is definitely getting the reading of the coolant at it's hottest point (notwithstanding that it may have cooled ever so slightly in the 6" or so since it actually left the motor!!). There is of course a slight delay in the VDO registering initially as the thermostat doesn't open initially, but that's only a minute or so delay.

Hope this explains it all.


FollowupID: 368010

Follow Up By: Member - Captain (WA) - Tuesday, May 17, 2005 at 17:57

Tuesday, May 17, 2005 at 17:57
Hi Roachie,

Thanks for the welcome back. Looks like I might have stepped into an existing argument here - sorry!!!

I must admit, I have always thought (but never checked) that hot coolant goes to the bottom of the radiator and cold comes out the top! My reasoning for this is 3 fold;
1. The top radiator hose can "suck in" when old, this would only happend if it was a suction line.
2. The thermostat is definetley mounted in the bottom hose (well, was in my 80 when I replaced it) and I think that it would need the hot engine coolant to open it, otherwise how would it open if mounted on the "cold" side of the radiator (Thermostat never fully shuts off - always a small bypass flow)
3. Heat always rises, so more efficient to have hot in bottom of radiator trying to flow to top.

But I have never checked this, just assumed it. But, its really easy to prove. Simply place a hand on the bottom hose then the top hose and see which is hotter. If the hand test cannot tell the difference, a temp guage even on the outside of the hose will tell. Certainly not worth arguing about because one of us is wrong!!!! Will try it as soon as I get the chance.

Now for the second question. IF you are wrong, will you change it?

Cheers mate


PS. Sorry for hijacking this thread.
FollowupID: 368017

Follow Up By: Member - Roachie (SA) - Tuesday, May 17, 2005 at 23:11

Tuesday, May 17, 2005 at 23:11

Check out post # 22490......this is where it all started. Somebody posted a link to a site in USA which shows the coolant does flow into the radiator via the top hose (as I have always believed).

Cheers mate

FollowupID: 368084

Follow Up By: Member - Captain (WA) - Tuesday, May 17, 2005 at 23:24

Tuesday, May 17, 2005 at 23:24

Just checked out the thread and certainly the consensus of opinion was top to bottom. I stand corrected!

But I will still measure the top and bottom hose temps just to make sure, its hard to imagine after all those years of not actually thinking about it, just assuming it. See, you are never to old to learn something.


FollowupID: 368086

Reply By: floyd - Tuesday, May 17, 2005 at 17:34

Tuesday, May 17, 2005 at 17:34
2 possible explanations:

1. Some of the older type hoses had a reinforcing metal spiralled rod through the hose that helped to keep the hose in its natural shape in order to maximise hose volume and coolant flow. If you squeeze one of these hoses you can sometimes feel the metal insert change shape. If they are old enough the metal spiral can break. Just take the hose off and have a look in. Answer is to replace.

2. As the rubber in most hoses gets old it can go really hard and keep shape in a stiff form. If you squeeze an old stiff hose it can feel like it is fracturing or braking. It even feels like you have smashed something inside. It can even be heard as you squeeze it. I have done this and the simple answer is that it is time to change your hoses. It may not leak after doing this however it will reduce the strength in the hose. The answer is replace it.

If you have any doubt about the condition of hoses, thermostats, senders and radiators then you should replace them It is far cheaper than cooking a motor. Flushing out system as per owners manual and putting in correct coolant is also advised to prolong engine life. Cutting corners usually ends up with bigger problems sooner or later.
AnswerID: 111655

Follow Up By: figtree - Tuesday, May 17, 2005 at 18:41

Tuesday, May 17, 2005 at 18:41
Thank you all for the suggestions,
The most likely explanation would be the layer of hard rubber got cracked when I pressed the hose - further pressing does not crack anything anymore. I wonder where is the crumbled rubber gone....

Anyway, I booked the truck in and will change the hoses, flush the radiator. This should fix it-will have mechanic check/give me the old hose, just to make sure there is no deposit. I just replaced cooling fluid/ flushed the radiator (with water only) a couple of months ago, but we purchased the truck 5 months ago and there is no way to know what kind of coolant was used before...

FollowupID: 368026

Follow Up By: Exploder - Tuesday, May 17, 2005 at 20:02

Tuesday, May 17, 2005 at 20:02
You can always mount a radiator filter on the top hose, which will grab any big particles coming out of the engine and stop them from entering the radiator.

You just clean the filter once a month if there is nothing in it then you know the cooling system is good and then just start checking it every 6 months
FollowupID: 368036

Reply By: Mark- Tuesday, May 17, 2005 at 21:34

Tuesday, May 17, 2005 at 21:34
Hot coolant enters the radiator via the top hose. The coolant loses temp as it moves down the radiator and creates a 'thermosyphon effect" ie it tends to want to fall as it cools and increases in density, thereby assisting the flow of coolant.

This is why it nearly its always top hoses which fail first - the are exposed to much higher temperatures.

There is an Australian made inline coolant filter available called a 'Tefba'
which mounts in the top hose. Its amazing what they pick up. Highly recommended.
AnswerID: 111703

Follow Up By: figtree - Tuesday, May 17, 2005 at 21:52

Tuesday, May 17, 2005 at 21:52

I just wonder, how does the filter affect the flow rate of the coolant? The mesh in the path of the flow effectively inhibits the flow, unless the cross, sectional area of the filter is much higher than of the hose. However, it seems to be working well for you....

I would guess that, different vechicles would have different requirements/tolerances to the flow impedance by the filter... do you have HJ61?

FollowupID: 368058

Follow Up By: Exploder - Tuesday, May 17, 2005 at 22:09

Tuesday, May 17, 2005 at 22:09
Gday Figtree

Put one on my first car not a 4WD but. It had been garaged for some years and had a lot of internal corrosion of the block from incorrect rad mixture for storage. After flushing the hole system and putting the filter on never had a problem with overheating agene.
FollowupID: 368065

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