Originally Posted By: Ed_Flecko
I have a 2004 Toyota Tacoma with the 2.4 motor, and they have cast iron blocks with aluminum heads. My Sister gave me the truck and it seems to run perfectly. It has appx. 158,000 miles and has always been maintained by my local dealer where it was purchased or by a reputable, small auto shop.
From reading some of the other newsgroup postings, it seems like a pretty common occurrence that these motors blow their head gaskets. I'm wondering, as a general rule, if motors with aluminum heads are susceptible to problems warping and then blowing their gaskets? Or, is it more likely only if someone has neglected their maintenance, coolant changes, etc.?
Is there any special maintenance, tricks, tips, etc., to maintaining motors with aluminum heads?
Thank you,
Ed
Hi Ed,
Again a post where my automotive knowledge is zero but your question has a direct industrial counterpart so maybe at the theoretical level (if not directly applicable to a car) it might give you some information to troubleshoot or maybe avoid the problem.
Sadly even on some industrial machines the lead engineer has C.P.A. rather than P.E. behind his name and let the problems begin.
One of these problems is cheaper/lighter materials. This is a situation we are encountering now with failures with increasing frequency on a lot of pumps and compressors that 20 years ago really didn’t exist.
Aluminum by definition has virtually the same strength to weight ratio as steel so it can be a substitute in certain applications BUT the thermal properties are a different story.
Depending on the heat and pressure ratio measured against the surface area, tension points, overall mass and any cooling- you can have a design that is already very close to a potential failure.
The variables that matter are the uniform thermal expansion coefficient of the component where it mates to the other dissimilar component. This is both overall and then hotspots. (In this case the actual firing part of the head that gets the most heat)
That creates all kinds of expansion stress related deviations in the bolted unit regardless of the type and number of fasteners. (Find a thermal or FEA breakdown picture on the net of a car head and see all the force areas and hot spots)
More often than not in my world, the “gasket” proper never failed but a change/spike/ set over time of the 2 mating surfaces created a minor dimensional or clamp change allowing the thermal/pressure to push into the gasket mating area.
This will almost immediately lead to the “blowtorch effect” and destroy the gasket. (I cannot assign that failure to the gasket because it was not designed to withstand such an effect and the enabler was outside the gasket)
I have also seen in some of those failures that the normal machining to put the surface in plane removed enough mass to actually speed up the next failure.
I have also seen (all other things being equal) where the parent thread and/or the fastener were dissimilar enough to cause uneven tension loss thus enabling distortion that sets under thermal cycles.
That’s not even considering the routine failure modes of overheating, over running or other usual suspects.
I don’t know how much of that directly relates to a car engine but I would think that those would be the same failure modes as we encounter in industry.
Give you something to look for and maybe measure against if nothing else.
I have a 2004 Toyota Tacoma with the 2.4 motor, and they have cast iron blocks with aluminum heads. My Sister gave me the truck and it seems to run perfectly. It has appx. 158,000 miles and has always been maintained by my local dealer where it was purchased or by a reputable, small auto shop.
From reading some of the other newsgroup postings, it seems like a pretty common occurrence that these motors blow their head gaskets. I'm wondering, as a general rule, if motors with aluminum heads are susceptible to problems warping and then blowing their gaskets? Or, is it more likely only if someone has neglected their maintenance, coolant changes, etc.?
Is there any special maintenance, tricks, tips, etc., to maintaining motors with aluminum heads?
Thank you,
Ed
Hi Ed,
Again a post where my automotive knowledge is zero but your question has a direct industrial counterpart so maybe at the theoretical level (if not directly applicable to a car) it might give you some information to troubleshoot or maybe avoid the problem.
Sadly even on some industrial machines the lead engineer has C.P.A. rather than P.E. behind his name and let the problems begin.
One of these problems is cheaper/lighter materials. This is a situation we are encountering now with failures with increasing frequency on a lot of pumps and compressors that 20 years ago really didn’t exist.
Aluminum by definition has virtually the same strength to weight ratio as steel so it can be a substitute in certain applications BUT the thermal properties are a different story.
Depending on the heat and pressure ratio measured against the surface area, tension points, overall mass and any cooling- you can have a design that is already very close to a potential failure.
The variables that matter are the uniform thermal expansion coefficient of the component where it mates to the other dissimilar component. This is both overall and then hotspots. (In this case the actual firing part of the head that gets the most heat)
That creates all kinds of expansion stress related deviations in the bolted unit regardless of the type and number of fasteners. (Find a thermal or FEA breakdown picture on the net of a car head and see all the force areas and hot spots)
More often than not in my world, the “gasket” proper never failed but a change/spike/ set over time of the 2 mating surfaces created a minor dimensional or clamp change allowing the thermal/pressure to push into the gasket mating area.
This will almost immediately lead to the “blowtorch effect” and destroy the gasket. (I cannot assign that failure to the gasket because it was not designed to withstand such an effect and the enabler was outside the gasket)
I have also seen in some of those failures that the normal machining to put the surface in plane removed enough mass to actually speed up the next failure.
I have also seen (all other things being equal) where the parent thread and/or the fastener were dissimilar enough to cause uneven tension loss thus enabling distortion that sets under thermal cycles.
That’s not even considering the routine failure modes of overheating, over running or other usual suspects.
I don’t know how much of that directly relates to a car engine but I would think that those would be the same failure modes as we encounter in industry.
Give you something to look for and maybe measure against if nothing else.
