EGR Coolers

Submitted: Thursday, Jul 30, 2015 at 15:52
ThreadID: 129601 Views:7462 Replies:3 FollowUps:2
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BT50s and Rangers with the 4 cyl. 3ltr turbo-diesel engine have a history of cooling problems, my research indicates that the exhaust gas cooler (EGR) is often the cause with the probable scenario being as follows.
Exhaust gas is recirculated into the engine inlet air to reduce exhaust pollution, as the gas is very hot it needs to be cooled first, so an EGR cooler is fitted. In this case the cooler is poorly designed and should be considered defective/faulty. There is only a small coolant flow through the cooler and this may be OK for average engine loads. The coolant is already hot as it flows from the cylinder head to the cooler, not from the radiator. But for long brisk drives, hot weather and heavy loads, or when the is radiator partially blocked, the exhaust gas entering the cooler is so hot that the coolant boils and vaporises halfway through the cooler. Like saltwater when the coolant vapourises small solid particles remain in the coolant flow path. These particles eventually collect in the top tank of the radiator progressively blocking the cores, the thermostat opens to counter the loss of cooling in the radiator. Reverse flushing of the radiator may clear the blockages. In the worse case the lack of coolant flow in the EGR cooler, due to it vapourising, results in the internal metal of the cooler failing allowing exhaust gas at higher pressure and temperature to flow into the coolant system ( similar to a blown head gasket or cracked head ), resulting in instant engine overheating and boiling, plus fairly costly repairs. The overheating can cause damage to the cylinder head and injector tips which are both very expensive to repair and may involve further problems.
Put simply at high loads the coolant flowing into the cooler is too hot and the flow too small to effectively remove the heat in the exhaust gas, the pollution control effect is minimised and by adding heat to the intercooled air entering the engine, engine power is adversely affected.
I have put these details to one of the manufacturers but they refuse to comment on the technical specifics and the nature and cause of the problem, they merely say that the vehicle was out of warranty and the repairs were not carried out by them. The absence of any rebuttal or comment on this sequence tends, I think, to confirm its validity. Other manufacturers are currently replacing air bags on cars well out of warranty.
Talking to spare parts suppliers, reviewing various search engines, forums and youtube indicates how common the EGR problems were with these companies plus others. The number of EGR coolers sold by dealers and replaced by repairers supports the contention that these vehicles should have been the subject of a recall &/or compensation payments to owners
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Reply By: Member -Dodger - Thursday, Jul 30, 2015 at 17:18

Thursday, Jul 30, 2015 at 17:18
Question Terry,
If one has had the EGR valve turned of electronically or have had it blocked would that make a difference in your scenario?
I used to have a handle on life, but it broke.

Cheers Dodg.

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Follow Up By: Les - PK Ranger - Thursday, Jul 30, 2015 at 18:02

Thursday, Jul 30, 2015 at 18:02
Yes, it would, see below reply.
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Follow Up By: Terry B16 - Friday, Jul 31, 2015 at 13:02

Friday, Jul 31, 2015 at 13:02
Dodger, Great answer from Les with some good links, but simply there has to be a flow of hot exhaust gas through the EGR cooler for the coolant to vapourise and for the internal failure of the EGR cooler. If the EGR valve remains closed the EGR cooler will still have exhaust gas pressure inside it, but there will be no heat as the flow has been stopped.
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Reply By: Les - PK Ranger - Thursday, Jul 30, 2015 at 18:22

Thursday, Jul 30, 2015 at 18:22
Yes, terrible design, very prone to failure.
Pretty much engineered to fail !!

You can deal with this a few ways, remembering that the EGR is a legal requirement, but then so is keeping lifts legal and a whole host of other things that are sometimes put aside by owners.

If you block the EGR system, you can then block the EGR cooler hoses (no need to bypass, they are independent of the general cooling system).

You need to block fully to enable a cooler disconnect, and if you do this with the blanking plates available, then you will get a CEL (check engine light) come on, and this would be a P0401 EGR Flow Insufficient Detected code.
You can get blanking plates with (I think) a 12mm hole . . . this allows enough flow to keep the CEL off, and a good portion of EGR gases out of the intake, but probably not safe to bypass the EGR cooler.

You can turn the CEL off for this code with an ECU tune, $$$ but other tweaks can be done for power / econ and certain things other than that (auto trans point shift for one).

Or, you can get a new experimental module as per the first post below and the second link to more detailed info about the mapper . . .
Is blocking the EGR a worthwhile mod ?
Manual mapper project

Besides the particulates being fed back into the intake manifold, there is also oil mist from the PCV system / valve being fed back in there with them, these 2 combined builds up as a black tar like gunk in the manifold, clogging up MAF sensor and eventually restricting flow in the intake system, sometimes clogging it nearly totally !
You can overcome this by eliminating one or the other (particulates or oil mist).
An oil catch can will take most of the oil mist out of the system, I installed one at 50k and my intake is clean apart form black dust form the EGR on the MAP.

The oil mist is also put through the intercooler, which can hold it (there is no drain) and eventually somewhat restrict the cooling action of the unit.
Have heard of people pouring a cup of oil out of their intercoolers.

See some info and other links here . . .
Has anyone fitted an oil catch can ?

I am currently using the experimental mapper, and will be happy if it just keeps the particulates out of my intake system.
Once happy it's reliable, I will use blanking plates on the EGR, and block the EGR cooler inlet / outlet.
AnswerID: 588129

Reply By: bigcol - Saturday, Aug 08, 2015 at 23:34

Saturday, Aug 08, 2015 at 23:34
I had a 3.0 litre BT50 and when the egr cooler decides to let go it's nowhere near as dramatic as you say.
The first thing you'll notice is a sound very similar to a squeaky fan belt that goes something like this. chirp chirp chirp chirp.
Next thing you'll notice is a little steam from the exhaust and the coolant level dropping. If I still owned one the first thing I would do is put a coolant level alarm on it.
Seen 3 of them do exactly that and my BT50 did just under 200 000Ks when I sold it to a Mazda service manager who stated that the egr cooler packs it in at around the 150000km mark and provided it's dealt with early, doesn't seem to do any long term damage to the engine.
Haven't seen any with solid particals blocking the radiator.
I also know of another where the owner just kept driving it an subsequently cooked the engine.
When it arrived at the mates workshop it had pumped all the coolant into the exhaust

By the way. My BT50 spent most of it's life towing a 1.5 tonne trailer. As a workhorse it made the other brands look ordinary. Especially the not so unbreakable one that I owned before
AnswerID: 589029

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